Proto-Sinaitic, also known as Proto-Canaanite was the first consonantal alphabet. Even a quick and cursory glance at its inventory of signs makes it very apparent of this script's Egyptian origin. Originally it was thought that the local West-Semitic population of Sinai aaround 1700 BCE, influenced by Egyptian culture had adopted a small number of hieroglyphic signs ( about 30 ) to write their own language. However, recent discoveries in mainland Egypt have compounded this scenario. Inscriptions dating to 1900 BCE written in what appears to be Proto-Sinaitic were found in Upper Egypt
Proto-Sinaitic soon spread to Canaan (Palestine), hence its other name, Proto-Canaanite, or old Canaanite script. It evolved locally into the Phoenician script which is its immediate descendant taking on a more linear ( less curved ) shape of its signs, everything else remained pretty much the same. South Arabian was also an early offshoot of Proto-Sinaitic, as its letters are very different in shape and order from Phoenician.
E.H. Palmer discovered the first Proto-Sinaitic inscriptions in 1869. Sir Flinders Petrie found about ten more in 1905 in the area of the temple of Serabit el Khadem. They were so called because they were found to pre-date the Nabataean inscriptions, which at that time had not yet been deciphered and were called the Sinaitic inscriptions
An inscription in one of the turquoise mines, the longest ever discovered, is a message from the leader of a certain mining group to one of the workers or his assistant. It reads: “Though, O Shaphan, collect from Ababa 8 minas “(of turquoise ). The signature is: “Shimea, groom of the chief of the caravaneers”.