diff --git a/eth2/beacon/chains/base.py b/eth2/beacon/chains/base.py
index d09f30edf6..e7017ee84a 100644
--- a/eth2/beacon/chains/base.py
+++ b/eth2/beacon/chains/base.py
@@ -1,38 +1,38 @@
 from abc import (
     ABC,
-    abstractmethod
+    abstractmethod,
 )
+import logging
 from typing import (
+    TYPE_CHECKING,
     Tuple,
     Type,
 )
 
-import logging
-
-from eth_typing import (
-    Hash32,
+from eth._utils.datatypes import (
+    Configurable,
 )
-from eth_utils import (
-    encode_hex,
-    ValidationError,
+from eth.db.backends.base import (
+    BaseAtomicDB,
 )
-
-from eth.db.backends.base import BaseAtomicDB
 from eth.exceptions import (
     BlockNotFound,
 )
 from eth.validation import (
     validate_word,
 )
-
-from eth._utils.datatypes import (
-    Configurable,
+from eth_typing import (
+    Hash32,
+)
+from eth_utils import (
+    ValidationError,
+    encode_hex,
 )
+
 from eth2._utils.ssz import (
     validate_imported_block_unchanged,
 )
-
-from eth2.beacon.db.chain import (  # noqa: F401
+from eth2.beacon.db.chain import (
     BaseBeaconChainDB,
     BeaconChainDB,
 )
@@ -40,11 +40,12 @@
     BlockClassError,
     StateMachineNotFound,
 )
-from eth2.beacon.state_machines.base import BaseBeaconStateMachine  # noqa: F401
 from eth2.beacon.types.blocks import (
     BaseBeaconBlock,
 )
-from eth2.beacon.types.states import BeaconState
+from eth2.beacon.types.states import (
+    BeaconState,
+)
 from eth2.beacon.typing import (
     FromBlockParams,
     Slot,
@@ -53,6 +54,11 @@
     validate_slot,
 )
 
+if TYPE_CHECKING:
+    from eth2.beacon.state_machines.base import (  # noqa: F401
+        BaseBeaconStateMachine,
+    )
+
 
 class BaseBeaconChain(Configurable, ABC):
     """
@@ -60,7 +66,7 @@ class BaseBeaconChain(Configurable, ABC):
     """
     chaindb = None  # type: BaseBeaconChainDB
     chaindb_class = None  # type: Type[BaseBeaconChainDB]
-    sm_configuration = None  # type: Tuple[Tuple[int, Type[BaseBeaconStateMachine]], ...]
+    sm_configuration = None  # type: Tuple[Tuple[Slot, Type[BaseBeaconStateMachine]], ...]
     chain_id = None  # type: int
 
     #
diff --git a/eth2/beacon/chains/testnet/__init__.py b/eth2/beacon/chains/testnet/__init__.py
new file mode 100644
index 0000000000..53c51a611d
--- /dev/null
+++ b/eth2/beacon/chains/testnet/__init__.py
@@ -0,0 +1,42 @@
+from typing import (
+    TYPE_CHECKING,
+)
+from eth2.beacon.chains.base import (
+    BeaconChain,
+)
+from eth2.beacon.state_machines.forks.xiao_long_bao import (
+    XiaoLongBaoStateMachine,
+)
+from eth2.beacon.state_machines.forks.serenity.configs import (
+    SERENITY_CONFIG,
+)
+from .constants import (
+    TESTNET_CHAIN_ID,
+)
+
+if TYPE_CHECKING:
+    from eth2.beacon.typing import (  # noqa: F401
+        Slot,
+    )
+    from eth2.beacon.state_machines.base import (  # noqa: F401
+        BaseBeaconStateMachine,
+    )
+    from typing import (  # noqa: F401
+        Tuple,
+        Type,
+    )
+
+
+TESTNET_SM_CONFIGURATION = (
+    # FIXME: Shouldn't access GENESIS_SLOT from a particular state machine configs.
+    (SERENITY_CONFIG.GENESIS_SLOT, XiaoLongBaoStateMachine),
+)  # type: Tuple[Tuple[Slot, Type[BaseBeaconStateMachine]], ...]
+
+
+class BaseTestnetChain:
+    sm_configuration = TESTNET_SM_CONFIGURATION
+    chain_id = TESTNET_CHAIN_ID
+
+
+class TestnetChain(BaseTestnetChain, BeaconChain):
+    pass
diff --git a/eth2/beacon/chains/testnet/constants.py b/eth2/beacon/chains/testnet/constants.py
new file mode 100644
index 0000000000..ad449a21db
--- /dev/null
+++ b/eth2/beacon/chains/testnet/constants.py
@@ -0,0 +1,3 @@
+
+
+TESTNET_CHAIN_ID = 5566
diff --git a/eth2/beacon/state_machines/forks/xiao_long_bao/__init__.py b/eth2/beacon/state_machines/forks/xiao_long_bao/__init__.py
new file mode 100644
index 0000000000..b66262c6a3
--- /dev/null
+++ b/eth2/beacon/state_machines/forks/xiao_long_bao/__init__.py
@@ -0,0 +1,40 @@
+from eth2.beacon.state_machines.base import (
+    BeaconStateMachine,
+)
+from eth2.beacon.state_machines.forks.serenity.blocks import (
+    SerenityBeaconBlock,
+    create_serenity_block_from_parent,
+)
+from eth2.beacon.state_machines.forks.serenity.state_transitions import (
+    SerenityStateTransition,
+)
+from eth2.beacon.state_machines.forks.serenity.states import (
+    SerenityBeaconState,
+)
+from eth2.beacon.types.blocks import (
+    BaseBeaconBlock,
+)
+from eth2.beacon.typing import (
+    FromBlockParams,
+)
+
+from .configs import (
+    XIAO_LONG_BAO_CONFIG,
+)
+
+
+class XiaoLongBaoStateMachine(BeaconStateMachine):
+    # fork name
+    fork = 'xiao_long_bao'
+
+    # classes
+    block_class = SerenityBeaconBlock
+    state_class = SerenityBeaconState
+    state_transition_class = SerenityStateTransition
+    config = XIAO_LONG_BAO_CONFIG
+
+    # methods
+    @staticmethod
+    def create_block_from_parent(parent_block: BaseBeaconBlock,
+                                 block_params: FromBlockParams) -> BaseBeaconBlock:
+        return create_serenity_block_from_parent(parent_block, block_params)
diff --git a/eth2/beacon/state_machines/forks/xiao_long_bao/configs.py b/eth2/beacon/state_machines/forks/xiao_long_bao/configs.py
new file mode 100644
index 0000000000..c221d668f0
--- /dev/null
+++ b/eth2/beacon/state_machines/forks/xiao_long_bao/configs.py
@@ -0,0 +1,17 @@
+from eth2.beacon.helpers import (
+    slot_to_epoch,
+)
+from eth2.beacon.state_machines.forks.serenity.configs import (
+    SERENITY_CONFIG,
+)
+
+
+SLOTS_PER_EPOCH = 4
+
+XIAO_LONG_BAO_CONFIG = SERENITY_CONFIG._replace(
+    SLOTS_PER_EPOCH=SLOTS_PER_EPOCH,
+    GENESIS_EPOCH=slot_to_epoch(SERENITY_CONFIG.GENESIS_SLOT, SLOTS_PER_EPOCH),
+    TARGET_COMMITTEE_SIZE=2,
+    SHARD_COUNT=2,
+    MIN_ATTESTATION_INCLUSION_DELAY=2,
+)
diff --git a/tests/core/p2p-proto/bcc/helpers.py b/tests/core/p2p-proto/bcc/helpers.py
index 16fee14bb1..a566f78d03 100644
--- a/tests/core/p2p-proto/bcc/helpers.py
+++ b/tests/core/p2p-proto/bcc/helpers.py
@@ -54,6 +54,7 @@ def __init__(self, db: BaseAtomicDB) -> None:
     coro_get_canonical_block_by_slot = async_passthrough('get_canonical_block_by_slot')
     coro_get_canonical_block_root_by_slot = async_passthrough('get_canonical_block_root_by_slot')
     coro_get_canonical_head = async_passthrough('get_canonical_head')
+    coro_get_canonical_head_root = async_passthrough('get_canonical_head_root')
     coro_get_finalized_head = async_passthrough('get_finalized_head')
     coro_get_block_by_root = async_passthrough('get_block_by_root')
     coro_get_score = async_passthrough('get_score')
diff --git a/tests/eth2/beacon/chains/test_chain.py b/tests/eth2/beacon/chains/test_beacon_chain.py
similarity index 100%
rename from tests/eth2/beacon/chains/test_chain.py
rename to tests/eth2/beacon/chains/test_beacon_chain.py
diff --git a/tests/eth2/beacon/chains/test_chains.py b/tests/eth2/beacon/chains/test_chains.py
new file mode 100644
index 0000000000..394fb52249
--- /dev/null
+++ b/tests/eth2/beacon/chains/test_chains.py
@@ -0,0 +1,13 @@
+import pytest
+from eth2.beacon.chains.testnet import TestnetChain
+
+
+@pytest.mark.parametrize(
+    "chain_klass",
+    (
+        TestnetChain,
+    )
+)
+def test_chain_class_well_defined(chain_klass):
+    chain = chain_klass(None)
+    assert chain.sm_configuration is not () and chain.sm_configuration is not None
diff --git a/tests/eth2/beacon/state_machines/forks/test_fork_classes.py b/tests/eth2/beacon/state_machines/forks/test_fork_classes.py
new file mode 100644
index 0000000000..e583057d1a
--- /dev/null
+++ b/tests/eth2/beacon/state_machines/forks/test_fork_classes.py
@@ -0,0 +1,20 @@
+import pytest
+
+from eth2.beacon.state_machines.forks.serenity import (
+    SerenityStateMachine,
+)
+from eth2.beacon.state_machines.forks.xiao_long_bao import (
+    XiaoLongBaoStateMachine,
+)
+
+
+@pytest.mark.parametrize(
+    "sm_klass",
+    (
+        SerenityStateMachine,
+        XiaoLongBaoStateMachine,
+    )
+)
+def test_sm_class_well_defined(sm_klass):
+    state_machine = sm_klass(chaindb=None, block=None)
+    assert state_machine.get_block_class()
diff --git a/trinity/db/beacon/chain.py b/trinity/db/beacon/chain.py
index 550dc35b45..4f7e029247 100644
--- a/trinity/db/beacon/chain.py
+++ b/trinity/db/beacon/chain.py
@@ -63,6 +63,10 @@ async def coro_get_canonical_block_root_by_slot(self, slot: int) -> Hash32:
     async def coro_get_canonical_head(self, block_class: Type[BaseBeaconBlock]) -> BaseBeaconBlock:
         pass
 
+    @abstractmethod
+    async def coro_get_canonical_head_root(self)-> Hash32:
+        pass
+
     @abstractmethod
     async def coro_get_finalized_head(self, block_class: Type[BaseBeaconBlock]) -> BaseBeaconBlock:
         pass
@@ -124,6 +128,7 @@ class AsyncBeaconChainDBPreProxy(BaseAsyncBeaconChainDB):
     coro_get_canonical_block_by_slot = async_method('get_canonical_block_by_slot')
     coro_get_canonical_block_root_by_slot = async_method('get_canonical_block_root_by_slot')
     coro_get_canonical_head = async_method('get_canonical_head')
+    coro_get_canonical_head_root = async_method('get_canonical_head_root')
     coro_get_finalized_head = async_method('get_finalized_head')
     coro_get_block_by_root = async_method('get_block_by_root')
     coro_get_score = async_method('get_score')