June, 1995: The Ice Age Comes to Magic
Ice Age brought with it the first serious exploration of "allied colors". While multicolored cards had been around since Legends, Ice Age explicitly built up the alliances between neighboring colors with cards like Tinder Wall, Norritt, and Orcish Lumberjack.
Ice Age would be followed by Homelands and then the first set designed as a sequel, Alliances. Many years later, Coldsnap would provide the third set for the Ice Age block (which up until then had included Homelands by default).