Maybe you should go for Pangaea. The sites aren't very fitting, but there are few very good reasons:
Pangaea is currently a stealth nation, and has good, fast, "mounted" sacred units.
Pangaean Heroine Harpy Queen auto-summons Harpies.
Pangaea has multiple special summon spells in its "Carrion Woods" theme. That theme also has lots of units no other nation can get, although I don't think Manikin/Mandragora constuction spells can net you them.
By changing Harpies yo your Eagles you can easily get what you want. If you want to keep heroes, you can replace Pan and Maenads, and make Harpy Queen summon slightly better harpies or something entirely else. If you don't care about heroes, you can make Pan the scout (would only work in turmoil though), Harpy Queen the mage-priest that summons eagles, and Maenads and Harpies to the Eagles that would be summoned.
You can either have Eagles replace Harpies in the recruit, or #clearrec and not add eagle/harpies.
You can use Valley of the Horse Brothers as one of their starting sites, and replace Horse Brother commander with one of their commanders. They could turn out elsewhere, but that site fits your nation and Glowing Hill (Van in Dom:PPP, Daoine Sidhe in DomII?) already does this for other nation's special unit.
Also, please check
this post if you already haven't. It is Duncanish's idea about Indian nation: "I've been tinkering with a nation based roughly along the lines of various Native American nations. But, the fantasy twist, it's a nation of shapeshifters. Fans of the White Wolf book line, Werewolf: The Apocolypse will recognize all of these things, as it's drawn from their line. "