House of Wessex in Hampshire's History
The period known as the House of Wessex emerged out of period when England was caught up in a series of internal wars as regions of the country struggled to achieve political power. Mercia was the strongest kingdom but when King Offa died in 796 then Wessex emerged as the leading kingdom and it was Wessex that eventually defeated the Vikings. Hampshire emerged as one of the shires of Wessex and took it's name at some point before A.D 750 'Hamtun-scire'. Winchester became it's centre and under the rule of that Wessex king, King Alfred the Great, whose ruling influence is still apparent today so Winchester became the capital of England and Southampton the most significant port outside of London.
This period from the beginning of the 9th century to the Norman invasion (with the slight hiccup of the Danish kings) put Wessex and Hampshire right at the heart of power and politics in England.
Egbert was King of Wessex from 802 - 839. When the King of Northumbria submitted to him in 829 he was given the title Bretwalda, ruler of Britain and so it was that the dynasty set to rule Wessex, including the area of Hampshire was to become the most powerful of the early Kingdoms.