Historical clue formulations

• Wide gap — 2020-01-12
• Chasm — 2017-12-17
• Waters south of the South, e.g. — 2008-03-25
• ___ war syndrome — 2007-11-06
• Chasm — 2005-03-31
• Split — 2000-03-18
• Persian ___ — 1999-01-04