Employing foreign mercenaries as royal guards is an ancient trend. The Pope employed Swiss guards starting with the Renaissance. The Basileus had his Varangian Guard. Even the Roman emperors briefly recruited an Imperial German Guard. The benefits are obvious: foreigners have no chance in any local political arena, and their loyalty lies with the guy paying their salaries, and any units whose fame crosses cultural boundaries must be skilled and famous indeed.
How far back does this go, though? Who was the first to intentionally employ a unit of fully foreign soldiers?
