What role does the Northern Alliance play in The Kite Runner?

There is very little mention of the Northern Alliance (aka
the United Islamic Front for the Salvation of Afghanistan, or UIF) in Khaled Hosseini's
novel, The Kite Runner. The Northern Alliance was the organization
that united all of the Afghan tribes that opposed the Taliban, fighting against the
Taliban during the 1990s while keeping a portion of Afghanistan out of Taliban hands.
Following the September 2001 terrorist attacks on American soil, U.S. troops joined with
the Northern Alliance fighters, and soon the nation was rid of Taliban rule. Near the
end of the novel, Amir mentions the Northern Alliance's role in taking control of the
country "and the Taliban scurried like rats into the caves." Previously, when Amir
returned to Pakistan to see Rahim Khan, Rahim introduced him to Farid, a Tajik who had
fought with Northern Alliance forces for two years in the Peshawar Valley in the "jihad"
against the Taliban. Farid was 14 when he joined his father in the fight to liberate
Afghanistan. His father was killed, and Farid lost several fingers and toes to
the wounds he received.