- Wano country of the past hints the world looked a lot different back then before void century
- Looks like the ancient weapons were used to reshape the world, the destruction of Lulusia using one and the sea levels rising implied that in this chapter too
- Imu says that's why he chose this high stronghold so if he ever started another void century again to reshape the world his place wouldn't get flooded
- But he needs the ancient weapons for that, and he needs them before the One Piece is found or it becomes too late