Lach (Polish pronunciation: pronounced [ˈlax]), Lyakh or Ljach is a surname.
[1] Ethnic Poles in Nowy Sącz (south-eastern Poland) also used the name, referring to themselves as Lachy Sądeckie.
According to Paweł Jasienica, it derives from the name of an ancient Polish tribe, the Lendians.
[2] Due to population resettlements of ethnic Poles after the Soviet annexation of eastern Polish territories (see Kresy), it is slightly more frequent in western Poland.
[3][4] In the Czech Republic and Slovakia, Lach served as a short form of the personal name Ladislav.