The expansion of Alba into the wider Kingdom of Scotland was a gradual process combining external conquest and the suppression of occasional rebellions with the extension of seigniorial power through the placement of effective agents of the crown. Neighbouring independent kings became subject to Alba and eventually disappeared from the records. In the ninth century the term "mormaer", meaning "great steward", began to appear in the records to describe the rulers of Moray, Strathearn, Buchan, Angus and Mearns, who may have acted as "marcher lords" for the kingdom to counter the Viking threat. Later the process of consolidation is associated with the feudalism introduced by David I, which, particularly in the east and south where the crown's authority was greatest, saw the placement of lordships, often based on castles, and the creation of administrative sheriffdoms, which overlay the pattern of local thegns. It also saw the English "earl" and Latin "comes" begin to replace the "mormaers" in the records. The result has been seen as a "hybrid kingdom, in which Gaelic, Anglo-Saxon, Flemish and Norman elements all coalesced under its 'Normanised', but nevertheless native lines of kings".