Archaeology
Archaeological finds support the written sources. Late Sarmatian sites were first identified with the historical Alans by P.D. Rau (1927). Based on the archaeological material, they were one of the Iranian-speaking nomadic tribes that began to enter the Sarmatian area between the middle of the 1st and the 2nd century.
The Alani were first mentioned in Roman literature in the 1st century and were described later as a warlike people that specialized in horse breeding. They frequently raided the Parthian empire and the Caucasian provinces of the Roman Empire. In the Vologeses inscription one can read that Vologeses I, the Parthian king, in the 11th year of his reign, battled Kuluk, king of the Alani.
This inscription is supplemented by the contemporary Jewish historian, Josephus (37–100), who reports in the Jewish Wars (book 7, ch. 8.4) how Alans (whom he calls a "Scythian" tribe) living near the Sea of Azov, crossed the Iron Gates for plunder and defeated the armies of Pacorus, king of Media, and Tiridates, King of Armenia, two brothers of Vologeses I (for whom the above-mentioned inscription was made):
4. Now there was a nation of the Alans, which we have formerly mentioned somewhere as being Scythians, and inhabiting at the Lake Meotis. This nation about this time laid a design of falling upon Media, and the parts beyond it, in order to plunder them; with which intention they treated with the king of Hyrcania; for he was master of that passage which king Alexander shut up with iron gates. This king gave them leave to come through them; so they came in great multitudes, and fell upon the Medes unexpectedly, and plundered their country, which they found full of people, and replenished with abundance of cattle, while nobody durst make any resistance against them; for Pacorus, the king of the country, had fled away for fear into places where they could not easily come at him, and had yielded up everything he had to them, and had only saved his wife and his concubines from them, and that with difficulty also, after they had been made captives, by giving them a hundred talents for their ransom. These Alans therefore plundered the country without opposition, and with great ease, and proceeded as far as Armenia, laying all waste before them. Now, Tiridates was king of that country, who met them and fought them but had luck to not have been taken alive in the battle; for a certain man threw a net over him from a great distance and had soon drawn him to him, unless he had immediately cut the cord with his sword and ran away and so, prevented it. So the Alans, being still more provoked by this sight, laid waste the country, and drove a great multitude of the men, and a great quantity of the other prey they had gotten out of both kingdoms, along with them, and then retreated back to their own country.
Flavius Arrianus marched against the Alani in the 2nd century and left a detailed report (Ektaxis kata Alanoon or 'War Against the Alans') that is a major source for studying Roman military tactics, but doesn't reveal much about his enemy. In the late 4th century, Vegetius conflates Alans and Huns in his military treatise — Hunnorum Alannorumque natio, the "nation of Huns and Alans" — and collocates Goths, Huns and Alans, exemplo Gothorum et Alannorum Hunnorumque.
In Cathay and the Way Thither, 1866, Henry Yule writes:
The Alans were known to the Chinese by that name, in the ages immediately preceding and following the Christian era, as dwelling near the Aral, in which original position they are believed to have been closely akin to, if not identical with, the famous Massagetæ. Hereabouts also Ptolemy (vi, 14) appears to place the Alani-Scythæ, and Alanæan Mountains. From about 40 B.C. the emigrations of the Alans seem to have been directed westward to the Lower Don; here they are placed in the first century by Josephus and by the Armenian writers; and hence they are found issuing in the third century to ravage the rich provinces of Asia Minor. In 376 the deluge of the Huns on its westward course came upon the Alans and overwhelmed them. Great numbers of Alans are found to have joined the conquerors on their further progress, and large bodies of Alans afterwards swelled the waves of Goths, Vandals, and Sueves, that rolled across the Western Empire. A portion of the Alans, however, after the Hun invasion retired into the plains adjoining Caucasus, and into the lower valleys of that region, where they maintained the name and nationality which the others speedily lost. Little is heard of these Caucasian Alans for many centuries, except occasionally as mercenary soldiers of the Byzantine emperors or the Persian kings. In the thirteenth century they made a stout resistance to the Mongol conquerors, and though driven into the mountains they long continued their forays on the tracts subjected to the Tartar dynasty that settled on the Wolga, so that the Mongols had to maintain posts with strong garrisons to keep them in check. They were long redoutable both as warriors and as armourers, but by the end of the fourteenth century they seem to have come thoroughly under the Tartar rule; for they fought on the side of Toctamish Khan of Sarai against the great Timur.
Read more about this topic: Alans