Scottish Gaelic, also known as Scots Gaelic or simply Gaelic, is a Celtic language native to the Gaels of Scotland. As a member of the Goidelic branch of Celtic, Scottish Gaelic, alongside both Irish and Manx, developed out of Old Irish. It became a distinct spoken language sometime in the 13th century in the Middle Irish period, although a common literary language was shared by the Gaels of both Ireland and Scotland until well into the 17th century. Most of modern Scotland was once Gaelic-speaking, as evidenced especially by Gaelic-language place names.