The geographical territory of Caucasia includes areas which have been referred to, in various forms, in geographical, historical and even literary texts. Studies on the history of Caucasia in different eras show that not only this region was not originally called by this name, but, later on, this name was not used for what is now modern Caucasia. Studies show that each part of Caucasia was referred to by a specific name, based on the tribal characteristics of its inhabitants or the lineage of its rulers. Modern Caucasia is divided into the southern and northern parts. In the works of some of the Muslim historians and geographers northern Caucasia is not mentioned at all and those which have referred to it have used specific names for each part of it. Hence, they have called the regions around the Caucasus Mountains in northern Caucasia, in which the Khazar inhabited, the country of the Khazar. This research attempts to investigate the historical geography of Caucasia, its cause of denomination and its geographical boundaries. Historical and geographical books written about the first ten centuries Hijri (S. A. W) - within which most of historical-geographical books are written- along with library documents are used with a descriptive-analytic methodology to reveal Muslim historians and geographers’ viewpoint on Caucasia.