Now I also found this page (
http://www.atem.nl/CIV/NED/NH001.HTM) and I'll translate it for you to clear things up. The name of certain places are given and you could map it to present day maps.
Northwest Netherlands in the early Middle Ages
The landscape of our region at the start of our calendar era was very different from today, but reliable maps on which important historical events can be marked which preceded the last 500 years scarce.
The schematic map inserted here gives us an impression of how our region would have looked like in times of
Karel de Grote (Charlemagne). This landscape has probably only changed after the eleventh century, through the breach between the North Sea and the South Sea, causing the separation of Frisia and Holland.
On the map the following places, among others, are indicated: 1. Dockinga (Dokkum), 2. Groninga (Groningen), 3. Stauria (Starum/Stavoren), 4. Urck (Urk, in the present day northeast polder), 5. Alcmaria (Alkmaar), 6. Haarlhem (Haarlem), 7. Litte (?), 8. Bracola (?), 9. Trajectum Vetus (Utrecht), 10. Daventria (Deventer).
It is hard to tell how reliable the image provided by this map is. Accurate land surveying was non-existent during these times. The landscape must have partially consisted of marshy, difficult to access, bog forests and the data could be from various sources.
The big lake between the bog area and the higher grounds must have originated long before our calendar era. Roman writers mention it as
Flevo or
Flevum and in chronicles of the early middle ages the names
Almari and
Almeri appear. The name
Zuiderzee (South Sea) probably became fashionable only after the breach from the Marsdiep (the Marsdiep is the area between the island of Texel -pronunciation: Tessel- and North Holland).
The
Isala Nova (the south to north flowing river on the right side of the map) probably originated in Roman times as a connection dug between the Rhine and the Old IJssel. The Roman Pomponius Mela mentions that the Rhine split up in a left branch (wherein the present day Old Rhine can be recognized, on the bottom left side of the map, for a long time the northern border of the Roman Empire), and that another branch broadened itself to a lake called Flevo, enclosing an island with the same name, and afterwards flowing to the sea like a normal river. In this the river on the map can be recognized. The in Roman sources mentioned name
Fli for the mouth continues to live on in the
Vliestroom (Vlie Stream) between Vlieland and Terschelling.
The Isle Texela Pagus at the west side of the river was known in the Frankish time as a country that consisted of a big part of the present day North Holland. The deep-tide races at De Koog and between Eierland and Vlieland did not exist during the time of Charlemagne (742-814) and the areas in grey, eastern of the islands probably have been flooded during the ninth or tenth century. The draining river marked as Hisla Frisius might have led to the see before Roman Times. The Marsdiep and Texelstroom might have orginated somewhere halfway the eighth century. The breach from the Marsdiep to the South Sea has probably been created during the big storm surges of the twelfth century.
The map mentions at the east of the Fli Vistra and Astraga in which the Frisian lands of Westergo and Oostergo can be recognized. The sea entered deep into the Frisian lands at the Bornediep (Burdipe - presently known as Boorne or Boarn in Frisian) between Wistrachia (Terschelling) and Austrachia (Ameland) as the Borneda Sinus, the Middle Sea between Bolsward and Leeuwarden, which only disappeared during the the 13th and 14th century because of silting and poldering. From the east, the Middle Sea was fed by a river called Fluvius Born seu Bordena of which a Merovingian chronicle by Fredegarius describes how a large army of Charles Martel defeated and subjugated the Frisians under Duke Bubo in 734.
During the times represented by this map, there was no 'Holland'. The entire western coastal area, from Vlie to Zwin (an inlet at Brugge in Belgium) was inhabited by Frisians. The coastal area Khinemaria west of Waterlandia would become the homeland of the new duchy which would develop during the centuries after that to the important political factor Holland. The breach of the sea from Vistraga and Texela cut-off the West Frisians from the Frisian homeland which caused Western Frisia to form a natural entity with Holland. The South Sea saw the development of extensive marine trade that sailed to the Oostzee (East Sea - Baltic Sea) and later from the West Frisian trading centers into Easter Asia.
The breach of the sea through the old bog areas probably has not only wiped out entire communities, but possibly has also stimulated opportunities for new developments.
PS Also note how all the major seas in most languages are named after the geography in respect to the Frisians. The Frisians were well known seamen which was an important reason for the Romans to call the North Sea Mare Frisicum. The sea south of their lands was called the South Sea (Zuiderzee), the sea north of their lands was called North Sea (Noordzee), the sea east of their lands was called East Sea (Oostzee, even the Fins call it that way, even though the sea is west of them) and the sea which split their lands in half was called the Middle Sea (Middelzee, the present day municipality of 't Bildt is located at where the mouth of the sea used to be).
PPS when you realize that the entire coastal area between the Saxons and the Angeln up to the place where they crossed the English Channel in order to invade England was inhabited by Frisians and because of the proficient seamanship of the Frisians, it is easy to understand why English and Frisian are so similar. It is even possible that, albeit on a smaller scale, the Frisians took part in the invasion of Britain.