Interesting tidbit (thanks to Emet m'Tziyon). Publius Cornelius Tacitus mentions this in his Histories:
[5.1] EARLY in this year Titus Caesar, who had been selected by his father to complete the subjugation of Judaea, and who had gained distinction as a soldier while both were still subjects, began to rise in power and reputation, as armies and provinces emulated each other in their attachment to him. The young man himself, anxious to be thought superior to his station, was ever displaying his gracefulness and his energy in war. By his courtesy and affability he called forth a willing obedience, and he often mixed with the common soldiers, while working or marching, without impairing his dignity as general. He found in Judaea three legions, the 5th, the 10th, and the 15th, all old troops of Vespasian's. To these he added the 12th from Syria, and some men belonging to the 18th and 3rd, whom he had withdrawn from Alexandria. This force was accompanied by twenty cohorts of allied troops and eight squadrons of cavalry, by the two kings Agrippa and Sohemus, by the auxiliary forces of king Antiochus, by a strong contingent of Arabs, who hated the Jews with the usual hatred of neighbours, and, lastly, by many persons brought from the capital and from Italy by private hopes of securing the yet unengaged affections of the Prince. With this force Titus entered the enemy's territory, preserving strict order on his march, reconnoitring every spot, and always ready to give battle. At last he encamped near Jerusalem.

So while students of the Bible may not be surprised, Tacitus shows that Arab hatred of Jews pre-dates Islam by many centuries.

I imagine that they were only upset by the "occupation" of Canaanite land a millenium earlier, and that they were just trying to help the Romans uphold international law.