\The Augments trilogy specifically states 20th century in dialogue, which aired after Archer spoke of his great-grandfather in the Eugenics Wars.
Two separate eugenics wars nearly a century apart, we had more than one world war.
A possible timeline of Khan rise (and fall from) power could be this ...
In 1984 following the assassinated of Indira Gandhi, Noonien Singh age 34 become leader of the Indian government
1985, the charismatic Singh forges a political alliance with Pakistan.
1989, Afghanistan recovering from the Russian withdraw and series of weak coalition governments join Singh's alliance.
1991, with the covert assistance of the western powers, Myanmar/Burma's military junta is over thrown in a coup, India formally annexes Burma.
!991 India annexes Thailand.
1992, Indonesia's government is now largely composed of Singh loyal supermen and non-superman puppets.
1992, following the Gulf War Singh employs proxies to seize control of Iraq, that same year, surrounded and threaten with India's nuclear weapons, Iran quietly comes under Singh's control.
By the end of 1992, at age 42 Singh was the leader of one quarter of the world (or one quarter of the population). His government's senior leadership, now almost entirely comprised of other supermen, proclaims Noonen Singh "Khan."
1993, in over forty countries, more supermen seize power, mostly through intrigue, assassination, power plays and military coups. All of these governments are tyrannies.
1993, one group of Supermen in Indonesia and another group in Thailand seize control from Khan loyalists and separately succeed from India.
1996, by the beginning of this year most of the supermen are fighting each other and the non-supermen lead nations around them too. Internal revolutions combined with attacks from other supermen at his flanks lead to Khan being over thrown by his own people.
