Hello there! I am from the future! If anyone can read this I know of the game you're talking about. It's called Legend of Dragon Island and very Warcraft 1/2-esque. I have a copy of the game lying around my house somewhere and can tell you a little about it.
There are 3 factions: Tang Bandits (Chinese), Shilla (Korean) and Samurai (Japanese). Each had similar units and structures but they also had specialised units that could be summoned from an Ashes Tower. I believe there was a Dragon, Turtle and Tiger respectively. There was also a Tombstone where the souls of your mortal units would fly towards and gave you special abilities.
There were 2 resources: gold and food. Food would grow after every rainy season I believe. Gold had to be extracted on top of specific spots.
Edit: some more stuff I'd like to add - ________________________________________________________________
There were dozens of missions and no multiplayer AFAIR. Tang Bandits had a fire sorceress chick that did insane damage granted she had the energy for it. You could build ships, simple siege units like ballistae and even PAPER KITES which had 2x the health of infantry units. 640 health kites vs 320 for archers, swordsmen and spearmen.
It would rain from time to time and this would help the crops grow again. Funnily the kite units would take damage over time and eventually get destroyed by the rain.
Each faction had a headquarters, barracks, dock, ashes tower, tombstone, siegeworks and various other typical RTS structures. It was very Warcraft 1/2-esque in style.