The Jews of Arabia, enjoying complete liberty, and being subjected to no restraint, were able to defend their religious opinions without fear, and to communicate them with impunity to their heathen neighbors. The Arab mind, susceptible to intellectual promptings, was delighted with the simple, sublime contents of the Bible, and by degrees certain Jewish conceptions and religious ideas became familiar and current in Arabia. The Arabian Jews made their neighbors acquainted with a calendar-system, without which the latter were completely at sea in the arrangement of their holy seasons; learned Jews from Yathrib taught the Arabs to insert another month in their lunar year, which was far in arrear of the solar year. The Arabs adopted the nineteen-years cycle of the Jews (about 420), and called the intercalary month Nasi, doubtless from the circumstance that the Jews were accustomed to receive their calendar for the festivals from their Nasi (Patriarch). The Jews even succeeded in instructing the Arabs in regard to their historical origin, concerning which their memories were void, and in their credulity the latter accepted this genealogy as the true one. It was of great consequence to the Jews to be regarded and acknowledged by the Arabs as their kinsmen, and too many points of social interest were bound up with this relationship for them to allow it to escape their attention. The holy city of Mecca (Alcharam), the chief city of the country, was built round an ancient temple (Kaaba, the Square), or more properly, round a black stone; for all Arabs it was an asylum, in which the sword durst not quit the sheath. The five fairs, the most important of which was at Okaz, could be frequented only in the four holy months of the year, when the truce of God prevailed. Whoever desired to take advantage of these periods and to enjoy security of life in the midst of a warlike people, not over-scrupulous in the matter of shedding blood, was obliged to establish his relationship to the Arabs, otherwise he was excluded from these privileges.