diff --git a/chainsyncer/backend/memory.py b/chainsyncer/backend/memory.py
index 2ac291d..e49102f 100644
--- a/chainsyncer/backend/memory.py
+++ b/chainsyncer/backend/memory.py
@@ -1,5 +1,6 @@
 # standard imports
 import logging
+import uuid
 
 # local imports
 from .base import Backend
@@ -20,19 +21,38 @@ class MemBackend(Backend):
     :type target_block: int
     """
 
-    def __init__(self, chain_spec, object_id, target_block=None, block_height=0, tx_height=0, flags=0):
+    def __init__(self, chain_spec, object_id):
         super(MemBackend, self).__init__(object_id)
         self.chain_spec = chain_spec
-        self.block_height_offset = block_height
-        self.block_height_cursor = block_height
-        self.tx_height_offset = tx_height
-        self.tx_height_cursor = tx_height
-        self.block_height_target = target_block
         self.db_session = None
-        self.flags = flags
+        self.block_height_offset = 0
+        self.block_height_cursor = 0
+        self.tx_height_offset = 0
+        self.tx_height_cursor = 0
+        self.block_height_target = None
+        self.flags = 0
+        self.flags_start = 0
+        self.flags_target = 0
         self.filter_names = []
 
 
+    @staticmethod
+    def custom(chain_spec, target_block, block_offset=0, tx_offset=0, flags=0, flags_count=0, *args, **kwargs):
+        object_id = kwargs.get('object_id', str(uuid.uuid4()))
+        backend = MemBackend(chain_spec, object_id)
+        backend.block_height_offset = block_offset
+        backend.block_height_cursor = block_offset
+        backend.tx_height_offset = tx_offset
+        backend.tx_height_cursor = tx_offset
+        backend.block_height_target = target_block
+        backend.flags = flags
+        backend.flags_count = flags_count
+        backend.flags_start = flags
+        flags_target = (2 ** flags_count) - 1
+        backend.flags_target = flags_target
+        return backend
+
+
     def connect(self):
         """NOOP as memory backend implements no connection.
         """
@@ -67,13 +87,22 @@ class MemBackend(Backend):
         return ((self.block_height_cursor, self.tx_height_cursor), self.flags)
 
 
+    def start(self):
+        """Get the initial syncer state
+
+        :rtype: tuple
+        :returns: block height / tx index tuple, and filter flags value
+        """
+        return ((self.block_height_offset, self.tx_height_offset), self.flags_start)
+
+
     def target(self):
         """Returns the syncer target.
 
         :rtype: tuple
         :returns: block height / tx index tuple
         """
-        return (self.block_height_target, self.flags)
+        return (self.block_height_target, self.flags_target)
 
 
     def register_filter(self, name):
diff --git a/chainsyncer/backend/sql.py b/chainsyncer/backend/sql.py
index a930ce5..4eaaf9b 100644
--- a/chainsyncer/backend/sql.py
+++ b/chainsyncer/backend/sql.py
@@ -148,6 +148,30 @@ class SQLBackend(Backend):
         return (target, filter_target,)
 
 
+    @staticmethod
+    def custom(chain_spec, target_block, block_offset=0, tx_offset=0, flags=0, flag_count=0, *args, **kwargs):
+        """
+
+        :param flags: flags bit field
+        :type flags: bytes
+        :param flag_count: number of flags in bit field
+        :type flag_count: 
+        """
+        session = SessionBase.create_session()
+        o = BlockchainSync(str(chain_spec), block_offset, tx_offset, target_block)
+        session.add(o)
+        session.commit()
+        object_id = o.id
+  
+        of = BlockchainSyncFilter(o, flag_count, flags, kwargs.get('flags_digest'))
+        session.add(of)
+        session.commit()
+
+        session.close()
+
+        return SQLBackend(chain_spec, object_id)
+
+
     @staticmethod
     def first(chain_spec):
         """Returns the model object of the most recent syncer in backend.
diff --git a/chainsyncer/db/models/filter.py b/chainsyncer/db/models/filter.py
index e8b0a12..ee5339b 100644
--- a/chainsyncer/db/models/filter.py
+++ b/chainsyncer/db/models/filter.py
@@ -38,7 +38,9 @@ class BlockchainSyncFilter(SessionBase):
     count = Column(Integer)
 
 
-    def __init__(self, chain_sync, count=0, flags=None, digest=zero_digest):
+    def __init__(self, chain_sync, count=0, flags=None, digest=None):
+        if digest == None:
+            digest = zero_digest
         self.digest = digest
         self.count = count
 
diff --git a/chainsyncer/driver/poll.py b/chainsyncer/driver/poll.py
index 9fb7abf..1cbbf11 100644
--- a/chainsyncer/driver/poll.py
+++ b/chainsyncer/driver/poll.py
@@ -9,7 +9,8 @@ from chainsyncer.error import (
         NoBlockForYou,
         )
 
-logg = logging.getLogger(__name__)
+#logg = logging.getLogger(__name__)
+logg = logging.getLogger()
 
 
 
@@ -29,6 +30,7 @@ class BlockPollSyncer(Syncer):
         :rtype: tuple
         :returns: See chainsyncer.backend.base.Backend.get
         """
+        raise ValueError()
         (pair, fltr) = self.backend.get()
         start_tx = pair[1]
 
diff --git a/chainsyncer/driver/threadpool.py b/chainsyncer/driver/threadpool.py
index bedcef4..e62ffb0 100644
--- a/chainsyncer/driver/threadpool.py
+++ b/chainsyncer/driver/threadpool.py
@@ -115,7 +115,6 @@ class ThreadPoolHistorySyncer(HistorySyncer):
         pass
 
 
-    #def process(self, conn, block):
     def get(self, conn):
         if not self.running:
             raise SyncDone()
diff --git a/chainsyncer/driver/threadrange.py b/chainsyncer/driver/threadrange.py
new file mode 100644
index 0000000..d69adc4
--- /dev/null
+++ b/chainsyncer/driver/threadrange.py
@@ -0,0 +1,68 @@
+# standard imports
+import copy
+import logging
+import multiprocessing
+
+# local imports
+from chainsyncer.driver.history import HistorySyncer
+from .threadpool import ThreadPoolTask
+
+#logg = logging.getLogger(__name__)
+logg = logging.getLogger()
+
+
+def range_to_backends(chain_spec, block_offset, tx_offset, block_target, flags, flags_count, backend_class, backend_count):
+    block_count = block_target - block_offset
+    if block_count < backend_count:
+        logg.warning('block count is less than thread count, adjusting thread count to {}'.format(block_count))
+        backend_count = block_count
+    blocks_per_thread = int(block_count / backend_count)
+
+    backends = []
+    for i in range(backend_count):
+        block_target = block_offset + blocks_per_thread
+        backend = backend_class.custom(chain_spec, block_target - 1, block_offset=block_offset, tx_offset=tx_offset, flags=flags, flags_count=flags_count)
+        backends.append(backend)
+        block_offset = block_target
+        tx_offset = 0
+        flags = 0
+
+    return backends
+
+
+class ThreadPoolRangeTask:
+    
+    loop_func = None
+
+    def __init__(self, backend, conn):
+        pass
+
+
+    def foo(self, a, b):
+        return self.loop_func()
+
+
+class ThreadPoolRangeHistorySyncer(HistorySyncer):
+
+    def __init__(self, conn_factory, thread_count, backends, chain_interface, loop_func=HistorySyncer.loop, pre_callback=None, block_callback=None, post_callback=None, runlevel_callback=None):
+        if thread_count > len(backends):
+            raise ValueError('thread count {} is greater than than backend count {}'.format(thread_count, len(backends)))
+        self.backends = backends
+        self.thread_count = thread_count
+        self.conn_factory = conn_factory
+        self.single_sync_offset = 0
+        self.runlevel_callback = None
+
+        ThreadPoolRangeTask.loop_func = loop_func
+
+
+    def loop(self, interval, conn):
+        super_loop = super(ThreadPoolRangeHistorySyncer, self).loop
+        self.worker_pool = multiprocessing.Pool(processes=self.thread_count)
+        for backend in self.backends:
+            conn = self.conn_factory()
+            task = ThreadPoolRangeTask(backend, conn)
+            t = self.worker_pool.apply_async(task.foo, (backend, conn,))
+            print(t.get())
+        self.worker_pool.close()
+        self.worker_pool.join()
diff --git a/chainsyncer/unittest/base.py b/chainsyncer/unittest/base.py
index 2b2c120..d3ed7b3 100644
--- a/chainsyncer/unittest/base.py
+++ b/chainsyncer/unittest/base.py
@@ -12,7 +12,6 @@ from chainsyncer.error import NoBlockForYou
 logg = logging.getLogger().getChild(__name__)
 
 
-
 class MockConn:
     """Noop connection mocker.
 
diff --git a/tests/test_database.py b/tests/test_database.py
index 8978f02..2ea0b77 100644
--- a/tests/test_database.py
+++ b/tests/test_database.py
@@ -184,5 +184,16 @@ class TestDatabase(TestBase):
         self.assertEqual(flags, 5)
 
 
+    def test_backend_sql_custom(self):
+        chain_spec = ChainSpec('evm', 'bloxberg', 8996, 'foo')
+        flags = 5
+        flags_target = 1023
+        flag_count = 10
+        backend = SQLBackend.custom(chain_spec, 666, 42, 2, flags, flag_count)
+        self.assertEqual(((42, 2), flags), backend.start())
+        self.assertEqual(((42, 2), flags), backend.get())
+        self.assertEqual((666, flags_target), backend.target())
+
+
 if __name__ == '__main__':
     unittest.main()
diff --git a/tests/test_mem.py b/tests/test_mem.py
new file mode 100644
index 0000000..03d9a8f
--- /dev/null
+++ b/tests/test_mem.py
@@ -0,0 +1,29 @@
+# standard imports
+import unittest
+
+# external imports
+from chainlib.chain import ChainSpec
+
+# local imports
+from chainsyncer.backend.memory import MemBackend
+
+# testutil imports
+from tests.chainsyncer_base import TestBase
+
+
+class TestMem(TestBase):
+
+    def test_backend_mem_custom(self):
+        chain_spec = ChainSpec('evm', 'bloxberg', 8996, 'foo')
+        flags = int(5).to_bytes(2, 'big')
+        #flags_target = int(1024-1).to_bytes(2, 'big')
+        flag_count = 10
+        backend = MemBackend.custom(chain_spec, 666, 42, 2, flags, flag_count, object_id='xyzzy')
+        self.assertEqual(((42, 2), flags), backend.start())
+        self.assertEqual(((42, 2), flags), backend.get())
+        self.assertEqual((666, flags), backend.target())
+        self.assertEqual(backend.object_id, 'xyzzy')
+
+
+if __name__ == '__main__':
+    unittest.main()
diff --git a/tests/test_thread.py b/tests/test_thread.py
new file mode 100644
index 0000000..5c8893a
--- /dev/null
+++ b/tests/test_thread.py
@@ -0,0 +1,12 @@
+# standard imports
+import logging
+import unittest
+
+# test imports
+from tests.chainsyncer_base import TestBase
+
+
+class TestThreadRange(TestBase):
+
+    def test_hello(self):
+        ThreadPoolRangeHistorySyncer(None, 3)
diff --git a/tests/test_thread_range.py b/tests/test_thread_range.py
new file mode 100644
index 0000000..5a57646
--- /dev/null
+++ b/tests/test_thread_range.py
@@ -0,0 +1,56 @@
+# standard imports
+import unittest
+import logging
+
+# external imports
+from chainlib.chain import ChainSpec
+
+# local imports
+from chainsyncer.backend.memory import MemBackend
+from chainsyncer.driver.threadrange import (
+        range_to_backends,
+        ThreadPoolRangeHistorySyncer,
+        )
+from chainsyncer.unittest.base import MockConn
+
+# testutil imports
+from tests.chainsyncer_base import TestBase
+
+logging.basicConfig(level=logging.DEBUG)
+logg = logging.getLogger()
+
+
+class TestThreadRange(TestBase):
+
+    def test_range_split_even(self):
+        chain_spec = ChainSpec('evm', 'bloxberg', 8996, 'foo')
+        backends = range_to_backends(chain_spec, 5, 3, 20, 5, 10, MemBackend, 3)
+        self.assertEqual(len(backends), 3)
+        self.assertEqual(((5, 3), 5), backends[0].start())
+        self.assertEqual((9, 1023), backends[0].target())
+        self.assertEqual(((10, 0), 0), backends[1].start())
+        self.assertEqual((14, 1023), backends[1].target())
+        self.assertEqual(((15, 0), 0), backends[2].start())
+        self.assertEqual((19, 1023), backends[2].target())
+
+
+    def test_range_split_underflow(self):
+        chain_spec = ChainSpec('evm', 'bloxberg', 8996, 'foo')
+        backends = range_to_backends(chain_spec, 5, 3, 7, 5, 10, MemBackend, 3)
+        self.assertEqual(len(backends), 2)
+        self.assertEqual(((5, 3), 5), backends[0].start())
+        self.assertEqual((5, 1023), backends[0].target())
+        self.assertEqual(((6, 0), 0), backends[1].start())
+        self.assertEqual((6, 1023), backends[1].target())
+
+
+    def test_range_syncer(self):
+        chain_spec = ChainSpec('evm', 'bloxberg', 8996, 'foo')
+        backends = range_to_backends(chain_spec, 5, 3, 20, 5, 10, MemBackend, 3)
+
+        syncer = ThreadPoolRangeHistorySyncer(MockConn, 3, backends, self.interface)
+        syncer.loop(1, None)
+
+
+if __name__ == '__main__':
+    unittest.main()