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During the 13th century, when German settlers were invited to Ukraine by the princes of the Kingdom of Ruthenia, German words began to appear in the language spoken in Ukraine. Their influence would continue under Poland not only through German colonists but also through the Yiddish-speaking Jews. Often such words involve trade or handicrafts. Examples of words of German or Yiddish origin spoken in Ukraine include dakh (roof), rura (pipe), rynok (market), kushnir (furrier), and majster (master or craftsman).
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Due to heavy borrowings from Polish, German, Czech and Latin, early modern vernacular Ukrainian (prosta mova, "simple speech") had more lexical similarity with West Slavic languages than with Russian or Church Slavonic. By the mid-17th century, the linguistic divergence between the Ukrainian and Russian languages had become so significant that there was a need for translators during negotiations for the Treaty of Pereyaslav, between Bohdan Khmelnytsky, head of the Zaporozhian Host, and the Russian state.