There is evidence of collaboration and assimilation of Russian people with the local peoples in Siberia. Though the more Russian people advanced to the East, the less developed the local people were, and the more resistance they offered. In 1607–1610, the Tungus fought strenuously for their independence, but were subdued around 1623. The Buryats also offered some opposition, but were swiftly pacified. The most resistance was offered by the Koryak (on the Kamchatka Peninsula) and Chukchi (on the Chukchi Peninsula), the latter still being at the Stone Age level of development. Resistance by local people may have been the result of forced unfair terms, that recorders would have benefitted from omitting.