But Geth is actually a holdover from the first time Magic went to Mirrodin (in Mirrodin).
In fact, you know the vault that Geth is the lord of? That's the same one as Disciple of the Vault!
Here are the pre-Scars of Mirrodin flavor text references to Geth.
Mirrodin came out seven years ago, but magicthegathering.com was already here. So here's a snippet from October 20, 2003 that seems relevant today. Say hello to the original concept art for Ish Sah, the Vault of Whispers!
Right: A concept illustration of Ish Sah, the so-called Vault of Whispers by Mark Tedin, which became black's artifact land. The Vault is a huge metallic structure with architecture reminiscent of metal skeletons. The interior of the Vault is shrounded in mystery, but is said to be the lair of a black-aligned warlord named Geth who commands many Nim. (Geth does not appear on a Mirrodin card directly, but is referred to in the flavor texts of Barter in Blood, Terror, and the Vault of Whispers itself.)