<prompt> Translate the following text to EnglishIreland imekuwa ikikaliwa na watu tangu nyakati za kale, lakini historia ya Ireland inaanza na kuwasili kwa Celts karibu karne ya 6 KK, uvamizi wa kwanza wa Ireland ulioandikwa.  <response>: Ireland has been inhabited since very ancient times, but Irish history really begins with the arrival of the Celts around the 6th century b.c. , Irelands first documented invasion. 