Pecheneg under the Byzantines

[Timotheus]

Does anyone know of a good history of steppe people that covers the Pecheneg well? From what I am reading they were a fairly powerful group that was eventually destroyed by Kiev and Byzantium but then sources also tell me that the Byzantines made heavy use of Pecheneg mercenaries during the First Crusade.

Was this the Byzantines accepting groups of surviving Pecheneg warriors to use as soldiers after the Pecheneg Khanate had been destroyed? Or were there other steppe people allied to the Byzantines that happened to go by the same name?

Any information would be helpful.