At first, the Anglo-Saxons did help to keep the Scots and the Irish at bay.
However, their demands for continued help got larger and larger. First it was money, then it was land, and then it was more land.
They also knew how weak the British were and so, after a while, help turned to conquest and more and more Anglo-Saxons arrived from Europe to stake out and claim land for themselves. This was the beginning of Anglo-Saxon England.
