[1] The "Batavian island" in the Rhine river was mentioned by Julius Caesar in his commentary Commentarii de Bello Gallico.

[2] Much later Tacitus wrote that the Batavians who lived there had originally been a part of the Chatti, a tribe in Germany never mentioned by Caesar, who were forced by internal dissension to move to their new home.

[3] Tacitus also reports that before their arrival the area had been "an uninhabited district on the extremity of the coast of Gaul, and also of a neighbouring island, surrounded by the ocean in front, and by the river Rhine in the rear and on either side".

[4] In a more detailed description he writes: The island of the Batavi was the appointed rendezvous because of its easy landing-places, and its convenience for receiving the army and carrying the war across the river.

For the Rhine after flowing continuously in a single channel or encircling merely insignificant islands, divides itself, so to say, where the Batavian territory begins, into two rivers, retaining its name and the rapidity of its course in the stream which washes Germany, till it mingles with the ocean.

[5]Modern archaeologists disagree with Tacitus, noting that that island had a pre-Roman and pre-Germanic population, apparently already called the Batavians.

Caesar indeed had not only implied the existence of pre-Roman Batavians, but also mentioned that the Belgic Menapii of the Flemish coast had settlements stretching as far as the beginning of the delta, near the modern border with Germany.

Zosimus is the only classical author who claims that they had first crossed the Rhine during the Roman upheavals and subsequent Germanic breakthrough in 260 AD.

In the Carolingian and Ottonian periods in the early Middle Ages, Batavia, called Batua by the Franks, was an example of a Frankish gau that was based on much older Roman pagi.