The question of which areas of the earth are fit for human habitation and which ones are not is dealt with in several Hebrew scientific texts of the twelfth and thirteenth century. Medieval Jewish scholars such as Abraham bar [Hdotu]iyya, Samuel ibn Tibbon, and the three thirteenth-century Hebrew encyclopedists were familiar with theories of the oikoumene and its boundaries through Arabic sources. These Hebrew texts display a variety of views on the earth's habitability, all of which ultimately go back to antiquity. Whereas some texts adopted a division of the inhabited portion of the earth into seven climes, others divided the earth into five zones of temperature, of which two were habitable and three were not owing to extreme temperatures. Some of these Jewish authors also pay attention to the question of how climatological or astrological conditions in a given region influence the mental constitution of its inhabitants.