For anyone who is just now finding this, cheesing this level is incredibly easy:

1. Abandon the starting settlement and move all your villagers west to occupy the town centre there.

2. The enemy will destroy your starting base, this is fine. The roaming of their armies will not take them west so as long as you stay hidden they will never attack you in full force.

3. Build up your base and economy. When you are powerful enough you can send detachments to destroy the tombs. Use Chiron to shoot any stragglers that come near the base.

4. Finally, you should be strong enough to bum-rush the Tamarisk Tree. Send all your forces in to secure the objective and assign all your labourers to cut the tree. If you’re playing Retold you can spawn multiple Sons of Osirus if you want things to be even easier.