The Taliban declared the "Islamic Emirate of Afghanistan" on Thursday, marking a nail in the coffin of the US-backed Afghan government.
Zabihullah Mujahid tweeted the declaration and the new name on Thursday.
The group used the name for the country when it ruled it between 1996 and 2001, before it was taken from power by US-led forces.
It was then known for its oppressive regime, including for its treatment of women.