Actually i am AOE2 players but i really love AOE1 especially playing the campaign. While playing AOE2 and checking the civs and tech tree, it is weird actually that they have a civs should not be even in AOE2 but in AOE1 and get their campaigns too with other civs that i suggest, which they are:
1-Huns: to be honest, all people of aoe2 like Huns especially in voobly days, but do you know what is the funny here? Huns is the most stupid choice to be a civ rather than being aoe2 civ, but if they should add it, this civ should exist in aoe1 for sure, and if aoe1 will have any future expansions, then Huns must be in this expansion 100% especially against Romans campaign.
2-Celts: Celts actually a civ that begins in 6th century BC and reach their max expansion in 250 BC, and they should be in aoe1 too.
6-** Göktürk Khaganate