These bands as we know were influenced by blues musicians like John Lee Hooker, Muddy Waters and Howlin' Wolf. During the late 60's the British blues invasion and performances by Jimi Hendrix, Johnny Winter, Ten Years After and Mountain at Woodstock are other examples of blues heavy influence on rock and hard rock and of course Southern rock music.
Lynyrd Skynyrd will always be remembered as a southern rock band but their contribution and influences to country, rock and roll and hard rock are important to remember as well.