Genesis 36:6

And Esau had taken his wives and his sons and his daughters, and all the souls of his house, and his flocks and his cattle, and all the substance which he had gotten in the land of Kenaan, and had gone into another land; for there fell upon him a fear of Jakob his brother:

AND ESAU TOOK HIS WIVES, AND HIS SONS, AND HIS DAUGHTERS. This journey took place after his brother had returned from Haran and established himself in the land of Canaan, as it says here, and he went into a land away from his brother Jacob. It is possible that this was also after the death of their father. Now when his brother Jacob was still in Haran, Esau was already in Se’ir, as is written above! But the explanation of the matter is that Esau went to Se’ir in the days of the chieftains of the Horites, the inhabitants of the land, and he became a lord with a following of four hundred men while his children and family remained in the land of Canaan. It is possible that Esau had some land there in another location, in the plain, not on mount Se’ir. Therefore Scripture speaks of him as living in the land of Se’ir, the field of Edom. And after his brother returned to the land of Canaan he vacated before his coming for he knew that the land of Canaan was the inheritance of his brother which his father had given him in his blessing. So he took his sons… and all the souls of his house — a multitude of people — and went to Se’ir to settle there. He then fought with the sons of Se’ir the Horite, the inhabitants of the land, for perhaps they feared him, and they did not permit him to enter their territory into mount Se’ir, where the fortifications were. However, he settled in the field of Edom, in his original location, and the Eternal destroyed them from before them, and they succeeded them, and dwelt in their stead, as it said in Mishneh Torah. It therefore says there, Because I have given mount Se’ir unto Esau for a possession., 2:5.

מפני יעקב אחיו, seeing that Yaakov had bought the birthright, and by rights he was entitled to inherit the estate of his father Yitzchok, i.e. the land of Canaan. Therefore, Esau decided to vacate that land in favour of his brother.

ואת כל בהמתו, a generic term including all of his livestock.

וילך אל ארץ, to a land where previously he had been living on an ad hoc basis before Yaakov had returned from Lavan. Now, after Yaakov’s return, he decided to move there permanently. כי היה רכושם רב, the reason that Esau moved now was 1) because the combined herds of Yaakov and Esau were extensive, and Esau feared he would ultimately be forced to leave the land of Canaan as G’d had promised it to Yaakov’s children as their inheritance. After all, his father Yitzchok had said to him in 27,39 that whereas his inheritance would be משמני הארץ, “of the fat places of the earth,” nothing had been said to him indicating that he would own part of the land of Canaan. Perhaps his father had even told him that Mount Seir would be his. The Torah refers to this land as being Esau’s by right in Deuteronomy 2,5 as well as in Joshua 24,4. His claim to this region was therefore not only that of a conqueror, but one which had Divine approval.