These were made around 1am on Sept 11, 1999. Age of Kings had already gone gold, but the people working on the official strategy guide were needing images that showed the entire scenario and they were having great difficulty taking a bunch of normal screenshots and pasting them together in PhotoShop.
In response to this problem, I had the idea that would become the Full Map Screenshot, and implemented it on short notice. The feature would later be enhanced and made available to players in the Conquerors Expansion Pack.
These files are most likely the very first success tests of that feature. You can see that a Mean Filter was implemented between shots #1 and #2 (The Water blending shows it most clearly).