The dates, particularly from the fourth to the late sixth centuries, have very few contemporary sources and are largely later constructions by medieval chroniclers.
"[2][3] Although the timeline uses the annals for this period of history, information provided by these sources can be problematic, particularly with the earlier dates.
[7] Some sources say that the Saxon warriors were invited to come, to the area now known as England, to help keep out invaders from Scotland and Ireland.
Another reason for coming may have been because their land often flooded and it was difficult to grow crops, so they were looking for new places to settle down and farm.
The most controversial dates in the period—those from the fourth to the late sixth centuries—have very few contemporary sources, and are mainly derived from later attempts to construct Anglo-Saxon history.