Possible Clues:

• By the end of the morning the river gets to the old city
• Tatar Strait feeder
• 2700-mile Asian river
• River to the Sea of Okhotsk
• First of advance military units reach river on the Russian-Chinese border
• NE Asian river
• 2,700-mile-long Asian river
• River forming, in part, the border between Russia and China
• Border river between China and Russia
• River to the Strait of Tartary