 An important source for the period is the Anglo @-@ Saxon Chronicle , a collection of annals in Old English narrating the history of the Anglo @-@ Saxons . The Chronicle was a West Saxon production , however , and is sometimes thought to be biased in favour of Wessex . Charters dating from Beorhtwulf 's reign have survived ; these were documents which granted land to followers or to churchmen and were witnessed by the kings who had the authority to grant the land . A charter might record the names of both a subject king and his overlord on the witness list appended to the grant . Such a witness list can be seen on the Ismere Diploma , for example , where Æthelric , son of king Oshere of the Hwicce , is described as a " subregulus " , or subking , of Æthelbald of Mercia . 
