Ptolemy's Geography divided Asia on a similar basis. In the north is "Scythia this side of the Himalayas" and "Scythia beyond the Himalayas." To the south is "India on this side of the Ganges" and "India beyond the Ganges." Asia began on the coast of Anatolia ("land of the rising sun"). Beyond the Ganges and Himalayas (including the Tien Shan) were Serica and Serae (sections of China) and some other identifiable far eastern locations known to the voyagers and geographers but not to the general European public.
Where did Asia begin? 
on the coast of Anatolia