Much of the time , the most recent period being in the 13th century to the late 16th century , the Amu Darya emptied into both the Aral and the Caspian Seas , the latter via a large distributary called the Uzboy River .
Much of the time , the most recent period being in the 13th century to the late 16th century , the Amu Darya emptied into both the Aral and the Caspian Seas .