The island has been occupied since the Mesolithic period, and its history includes a time of Norse rule and a long period of domination by Clan MacLeod and Clan Donald. The 18th century Jacobite risings led to the breaking up of the clan system and subsequent Clearances that replaced entire communities with sheep farms, some of which also involved forced emigrations to distant lands. Resident numbers declined from over 20,000 in the early 19th century to just under 9,000 by the closing decade of the 20th century. Skye’s population increased by 4 per cent between 1991 and 2001. About a third of the residents were Gaelic speakers in 2001, and although their numbers are in decline, this aspect of island culture remains important.