The global Senate is the government of Aemon people.
Global Senate was founded by women Aemon few decades before 1999. The Senate was established for all male Aemon wiped out by a disease. And the Senate is controlled by female Aemon. Those female Aemon founded a stable planetary government. And the Senate decided to conclude an alliance with their Tau'ri brethren. (RPG: "Friends and Foes: Stargate Season Two")