The Batavi themselves are not mentioned by Julius Caesar in his commentary "Commentarii de Bello Gallico", although he is often thought to have founded his dynasty's Germanic bodyguard, which was at least in later generations dominated by Batavi. But he did mention the "Batavian island" in the Rhine river. The island's easternmost point is at a split in the Rhine, one arm being the Waal the other the Lower Rhine/Old Rhine (hence the Latin name "Insula Batavorum", "Island of the Batavi"). Much later Tacitus wrote that they had originally been a tribe of the Chatti, a tribe in Germany also never mentioned by Caesar (unless they were his "Suebi"), who were forced by internal dissension to move to their new home. The time when this happened is unknown, but Caesar does describe forced movements of tribes from the east in his time, such as the Usipetes and Tencteri.