Old English place-names were spread by migrations. They should be found in the home lands and in the places migrated to, the "target lands". The Angles, the Saxons and the Jutes, we are told, occupied small territories on, or close to, the neck of the Danish peninsula. These three peoples, probably speaking similar varieties of the West Germanic language, migrated to England in the fourth and fifth centuries.
Later, texts from England show strong regional differences often referred to as dialects of Old English. If this were so, the variations would not be evidence for the languages spoken in the home lands. Fortunately, we know that Old English is a learned construct created in England several centuries after the migration. Dialects could not have developed from it. Consequently regional variations of Old English probably echo the differences in the West Germanic language spoken in the home lands accentuated in England by geographical isolation and the increased number of speakers.
In the "home lands", we should expect place-names formed with "ton", "ham", "worth" and so on. Unfortunately this is not so. Bede explains this saying, "They all left and to this day (his day) their lands lie unoccupied".
Some moderns imagine waves of immigrants swamping the landscape and renaming everything. Eastern England is given as an example where the apparent scarcity of Celtic names is said to be due to intensive English settlement.
A third strong possibility is that there were very few names on record. Small farming and fishing groups, perhaps moving periodically, had no need for a central administration, little contact with the outside world and little need to record place-names. Place-names existed in the mouths of the population and died when they left. This is like Bede's explanation.
Traditionally the Angles occupied the region now called Angeln in Schleswig Holstein. Saxon lands were around the Elbe estuary.
Jutland is presumed to have been the home of the Jutes.
Although this is a late, scholarly, generalisation there is no reason to doubt its essential correctness.