Conversation so far:
When was the Russian colonial period for the Alaska Natives?
Arriving from Siberia by ship in the mid-eighteenth century, Russians began to trade with Alaska Natives.
What did the Alaska Natives and the Russians trade during the Russian colonial period?
The Russians were primarily interested in the abundance of fur-bearing mammals on Alaska's coast, as stocks had been depleted by over hunting in Siberia.
What did the Alaska Natives and the Russians hunt during the Russian colonial period?
Rather than hunting the marine life, the Russians forced the Aleuts to do the work for them.

Question: When did this period end?
Self-contained rewrite: When did the Russian colonial period for Alaska Natives end?