The history of swat for its very first human habitation (before 1st millennium BC) is obscure yet, there is plenty of evidence that takes swat 2,300 years back in history to 327 BC era. In its relatively recent history, swat valley was inhabited by Buddhists during the 2nd century BC.
Timeline of Swat History
Here is the timeline summary of the swat history.
From Prehistoric Times to Alexander the Great Era
The Buddhist Period
The Evidence of the Chinese Pilgrims
The Days of Hephthalites, or White Huns Period
The Time of Turk Shahis (Tou-kiue)
The Period of The Kingdom of Tibet
The Span of The Hindu Shahiya
The Ghaznavids Period
The Era of The Gurids
The Mongol Period
The Span of Babur and the Mughal Empire
The Yousafzai State of Swat
Merger with Pakistan and Current Period