Applying to something in the past
extending in scope or effect to a prior time or to conditions that existed or originated in the past
especially : made effective as of a date prior to enactment, promulgation, or impositio
(especially of legislation) taking effect from a date in the past.
"a big retroactive tax increase"
Here's a answer for you!
2. The growth of powerful empires in Europe and Asia
4. Applying to something in the past
5. The Great Wall of China
6. On the bank of a river or near an oasis
7. A runner passing a baton in a relay race
9. a network of empires