The Homelands () expansion, released after Ice Age and before Alliances, was originally considered to be a member of the Ice Age block, although it included none of the mechanics or themes of the block.
The Ice-Age block is the only block in Magic's history in which one expansion (Homelands) has been removed and replaced by a newer one (Coldsnap). This also means that Coldsnap is the only Modern legal set from this block.
Theme decks were not introduced until the Tempest block. But, because of the later addition of Coldsnap to this block, this block now has theme decks.