This paper examines the frequency dynamics of taxis complex sentences of various structural types in the texts in Chukchi, Koryak and Alutor. The high level of synthesis in the system
of Chukchi taxis complex sentences throughout all recorded history of this language is probably influenced by ancient Chukchi-Eskimo contacts. Koryak and Alutor demonstrate comparatively less synthesis, and besides the tendency to synthesis appeared in these two languages only in the 2nd half of the XX century, most likely as a result of contacts with the Russian language and destruction of the primordial ergative coreference mechanism. The result of the linguistic analysis concerning Chukchi-Eskimo contact induced influence on the system of Chukchi taxis sentences is confirmed by great genetic similarity between Chukchi and Eskimo people.