Historical clue formulations

• Border river between China and Russia — 2015-07-19
• Russia/China border river — 2012-08-08
• Russia/China border river — 2008-09-22
• Russia/China border river — 2005-03-10
• Russia/Manchuria boundary river — 2004-05-20
• Tatar Strait feeder — 2003-10-04
• Russia/Manchuria boundary river — 1999-12-02
• Asian border river — 1997-08-16
• China-Russia boundary river — 1997-02-20
• Manchurian border river — 1994-06-21