Tashkent was first settled some time between the 5th and 3rd centuries BC by ancient people as an oasis on the Chirchik River, near the foothills of the West Tian Shan Mountains. In ancient times, this area contained Beitian, probably the summer "capital" of the Kangju confederacy. Some scholars believe that a "Stone Tower" mentioned by Ptolemy and by other early accounts of travel on the Silk Road referred to this settlement (due to its etymology). This tower is said to have marked the midway point between Europe and China. Other scholars, however, disagree with this identification, though it remains one of four most probable sites for the Stone Tower.