The South Arabian alphabet was used primarily in the Sabaean and Minaean kingoms, located at the southern edge of the Arabian Peninsula. It is thought to have diverged from the Proto-Sinaitic alphabet as early as 1300 B.C.E., and a developing form appeared in Babylonia and near Elath, on the Gulf of Aqaba, between the 8th and 7th centuries B.C.E. The alphabet evolved into its proper form around 500 B.C.E., and continued to be used until around 600 C.E., when the entire Arabian Peninsula was converted to Islam and Arabic became the most important language.*

*http://www.ancientscripts.com/s_arabian.html