The kingdom of Yemen is the most important and powerful of these. It occupies a portion of the ancient Arabia Felix. Descendants of Kahtan and Himyar--names of African origin--its monarchs rule over the whole of southern Arabia from about 380 B.C., with but few interruptions. The capital is first at Mareb and then at Sana. The northern kingdoms are more or less tributary. The Persians, Greeks, and Macedonians make no attempts upon Arabia, if we except the frontier skirmishes of Antigonus and Ptolemy. Rome had an eye to its conquest. Pompey, the first to attempt it, is foiled, and it was not until B.C. 25 when Ælius Gallus, the prefect of Egypt, undertakes an expedition at the command of Augustus. His army is unable to support the hardships of the desert, and the following year the Arabs drive the remnant out. Later attempts under Trajan and Severus do not succeed beyond the frontier, and Bosrah and Petra mark the extreme limits of Roman dominion. A.D. 100 Probable date of the great flood of Arem or Mareb, which leads to the foundation of other Arab kingdoms. 529 The Abyssinians, under Aryat, invade Yemen, to avenge the Christians persecuted by =Dhu-Nowas= the king. Dhu-Nowas is killed, and the Abyssinians rule the kingdom until 605 when Saif, with the assistance of Chosroes the Great, restores the Kahtanee dynasty, but it becomes dependent on Persia. 634 Mohammedan conquest of Yemen. THE KINGDOM OF HIRA (195-610 A.D.) Next in importance to Yemen. It is situated in Irak. Founded about 195 A.D. by =Malik=, it is more or less under allegiance to the Persians, but exercises considerable control over the Mustareb Arabs. 529 =Mundhir III=, king of Hira, who has been driven from the throne by Kavadh I of Persia, because he is too powerful, invades Syria, cruelly ravaging the country as far as Antioch. He kills Harith, whom Kavadh has set over his kingdom, and is finally himself killed, in 554, by a Roman vassal. 610 Chosroes II puts an end to the kingdom of Hira. THE KINGDOM OF GHASSAN (300-636 A.D.) Founded about 300 by =Thalaba=, the first to take the name of king. His successors rule until 636, when =Djabala VI= surrenders to the Mohammedans. THE KINGDOM OF KINDEH A small kingdom, of Yemenite origin, which detaches itself from Irak in the fifth century A.D. and maintains its existence for about 160 years, when it is absorbed by the Mustarebs. THE MUSTAREB KINGDOMS The northern tribes inhabiting central Arabia, or Arabia Petræa, become consolidated into five kingdoms: Rabiah, in the east centre of the peninsula. Kais, or Kais-Ailan, in the north. Hawazin, in the north. Tamin, in the middle. They are, from the time of their foundation, more or less tributary to Yemen until