Ancient Syria, one of the relatively few territories whose name has remained virtually unchanged throughout history, also roughly corresponds to the size of the modern country of the same name. The region was initially dominated by the Hittite culture and fell under the influence of various others such as the Amorites, Egyptians, Assyrians, Babylonians and Persians.
While it was influenced by these cultures, and conducted considerable profitable trade with each, it was also home to one of the ancient world's highly advanced peoples.
The Phoenicians, a mixture of native coastal Syrians and Canaanites of biblical fame, were great contributors to the advancement of human civilization. The Phoenicians were not only the greatest seafaring race of the ancient world, significantly advancing the art of shipbuilding, but improved and developed iron working throughout the east. They also introduced Syria's greatest legacy to human civilization, the 30 letter Semitic alphabet, which formed the basis for the Greek alphabet, and therefore the languages of the western world.
Perhaps even more influential, though it's hard to argue with the development of their alphabet, was the impact of Phoenician colonization. Because of their vast network of sea trade and travel, independent Phoenician city-states were established all over the Mediterranean (discovering the Atlantic Ocean in the process), the most notable being that of Carthage. The Phoenician culture of Carthage flourished, and an empire that reached all corners of Europe and the Mid-East dominated ancient trade.
In Syria itself however, the independence of their culture was under constant strain. The Assyrian King Tiglath-Pileser III overran Syria in the mid 8th century BC and was followed by the Babylonians under Nebuchadnezzar II in the late 7th century. The Persians intervened in the 6th century and would dominate the area for 3 centuries, until the coming of Alexander the Great. Under the Persians, like most of their conquests, the natives were allowed considerable autonomous rule, and the region prospered. This brief respite from foreign conquest was short-lived however, as Alexander invaded and conquered in 333 BC. With him came an immense cultural change, where Western Hellenistic ideas and institutions came to dominate.
Though Alexander died shortly after his conquest in 323 BC, the region continued to fall under the control of Macedonian policy. His General, Seleucas, became heir to the lands and established a three century dynasty that would remain only until their great defeat at the hands of Rome. Under the Seleucids Syria continued to prosper and Greek influence grew considerably. Immigrants flocked to the region and new cities sprung up all over. Trade with European and Middle-Eastern neighbors continued to flourish and Syrian goods reached such far flung places as India and China. Advancement in irrigation, astronomy, philosophy and all the sciences marked Hellenized rule.
The Seleucids, however, fatally misunderstood the growing power of Rome. In the early 2nd century BC, King Antiochus III had achieved great gains for Syria, both to the west and east. Because of repeated disputes between the dynasties established by Alexander's former generals, Macedonia, the Ptolemies of Egypt and the Seleucids, war and territorial jockeying was nearly constant. While the growing Roman power slowly expanded east, after having already defeated Carthage, Antiochus ignored the threat and continued to expand his own borders westward. In 191 BC, a relatively small Syrian army of 10,000 met a Roman force of twice its size at the famous Spartan battlefield of Thermopylae. Under the command of Consul Manius Acilius Glabrio, Antiochus was crushed and was forced to flee back to Asia. Over the course of the next the next year, the Romans pressed their advantage and an army led by Scipio Africanus and his brother Gnaeus overwhelmed a hastily recruited Syrian army at Magnesia. With this defeat, the Seleucid dynasty began to falter and external pressures from Arab Nabataeans, Armenians and the Parthian Empire took its toll.
Within a century, Hellenized rule was virtually in shambles and the east was in complete political disarray. Into the void came Mithridates VI of Pontus, who with his own conquests, drew Rome's eye even farther east. The rampant spread of Piracy along the southern coast of modern Turkey (Cilicia, Lycia and Pamphylia) brought further Roman interference. In 66 BC, a campaign led by Pompey the Great essentially brought the whole region, Syria included, under Roman control. In 64 BC, Syrian Kings were ousted, and Pompey officially annexed Syria as a Roman province.
Under Roman rule, Syria would eventually prosper again. Despite serving as a frontier buffer zone, Syria's ports and trade routes with the far east were important economic forces. Grain, fruits, cloth, glass, wool, linen, textiles, pottery, timber and resin were all exported in abundance. Dyes too, especially the purple dye extracted from mollusks on the Syrian shore were of particular importance.
Much like Syria's entire ancient history, it did remain a battleground territory during the Roman era. Serving as a launching point against Parthia, into Judaea and elsewhere, as many as 4 legions were garrisoned in Syria at any one time. Legio III Gallica, VI Ferrata, X Fretensis, XII Fulminata, IIII Scythica and XVI Flavia all saw service prior to the split of the eastern and western empires. With that split, and the eventual fall of the West, Syria fell under Byzantine authority, but was under constant pressure from Persians. Eventually, in the 7th century AD, despite strong Christian Orthodox roots, Syria fell to Arab invasions and grew into an Islamic cultural center.