The variants of the family name in Russia

According to Alexander Beider "A Dictionary of Jewish Surnames from the Russian Empire"
Don-Yachia (Lutsin), Doniach (Riga, Drissa, Mogilyov), Donchio (Sebezh), Donchin (Riga, Lutsin, Rezhitsa, Sebezh, Novo-Alexandrovsk[Zarasay]). The surname is taken in the beginning of XIX century by the descendant of sefard families Ibn Jahja (Yachia), translated from arabic as "son of Jahi" . As a surname he has taken a name of the first owner of surname Ibn Jachia: Don (spanish. Mister) Jachia ibn Jachia.
The detailed description of this surname can be found in the magazine "Jüdische Familien Forschung" (Berlin 1924-1938) 1927:11:261-264 and 1932:30:457-462. Surnames Don-Yichie not present in Beider dictionary, but there are Doniachi, Daniach, Deniach, Donchi, Donchiy, Donchia, Dachia, Dachya, Dunjahin, Denachin, Duniachin - all of them he derive from Don-Yachia.