Alans migrations in the 4th-5th centuries. Red: migrations; Orange: military expeditions; Yellow: settlement areas.
The Alans or Alani (occasionally termed Alauni or Halani) were a group of Sarmatian tribes, nomadic pastoralists of the 1st millennium AD who spoke an Eastern Iranian language which derived from Scytho-Sarmatian and which in turn evolved into modern Ossetian.By the beginning of the 1st century, the Alans had occupied lands in the northeast Azov Sea area, along the Don and by the 2nd century had amalgamated or joined with the Yancai of the early Chinese records to extend their control all the way along the trade routes from the Black Sea to the north of the Caspian and Aral seas. The written sources suggest that from the end of the 1st century to the second half of the 4th century the Alans had supremacy over the tribal union and created a powerful confederation of Sarmatian tribes.
Dr Oric Basirov
CAIS series of lectures /SOAS, 26/4/2001
The earliest known reference to the Alans (Greek ALANOI, Latin ALANI), however, is not until the mid 1st century A.D; it appears that by then the Alans, in turn, had taken the place of the Sarmatians in Eastern Europe; both these Iranian peoples are frequently mentioned in Greek, Roman, and Byzantine sources as late as the middle of the fifth century A.D. Alans, with an identical etymological origin with the word Iran, are extensively covered, especially by Ammianus Marcellinus who states inter alia, that "Almost all of the Alans are tall and good looking, their hair is generally blond" (AM, XXX,2,21); they once ruled a vast territory stretching from the Caucasus to the Danube, but were gradually driven westwards by the invading Huns; however, unlike their predecessors the Cimmerians, Scythians and the Sarmatians, the Alans did not vanish from the history; indeed they settled in the Byzantine Empire and Western Europe, playing a vital role in the subsequent European affairs; nonetheless, one finds it very odd that they are not given the full credit they truly deserve for being an important force in medieval Europe. Rostovtzeff, the great Russian expert in Iranians of the steppes, once complained that "In most of the work on the period of migrations, the part played by the Sarmatians and especially by the Alans in conquest of Europe is almost ignored; but we must never forget that the Alans long resided in Gaul, that they invaded Italy, and that they came with the Vandals to Spain and conquered North Africa"; one can easily sympathise with the frustration of the great Russian scholar; unlike various German tribes and Slavs and hoards of Huns, Avars, Magyars and Bulgars, who dominate the historical literature dealing with the early Middle Ages, the Alans hardly receive a mention; yet, they were in fact the only non-Germanic people of the migration period to make important settlements in Western Europe, and for many years dominated the affairs of the late Roman Empire. In 421, soon after their arrival in Constantinople, the Alan general, Ardaburius (Ardapur), fighting for the Byzantine emperor Theodosius, defeated the army of the Sasanian Emperor, Bahram V, and took the fortified frontier city of Nisibus; after several more victorious campaigns in Italy he was made consul for the year 427; his son, Asp~r (aspwar, Saw~r), in 431 commanded a large army against Vandals and Alans in Africa, and was made consul for the year 434. Asp~r''s son, Ardaburius (named after his grandfather) was also made consul in 447; in 450 when the emperor Theodosius II died, Asp~r was offered the imperial throne by the senate of Constantinople; he declined the throne, but gave it to his subordinate, Marcian. In 451 Attila the Hun laid siege to Orleans the capital city of the Alans in central Gaul; their new king, with the remarkably Modern Persian name of Sangiban, successfully defended the city, and with the help of his Roman and Visigoth allies pushed Attila to Chalons in eastern France; in the famous battle of Chalons Western Europe was saved from the ravage of the Huns. From the mid fifth century A.D. onwards, Alans, now fully Christianised, gradually lost their Iranian language, and were eventually absorbed into the population of medieval Europe; as late as 575 one still comes across Iranian names, such as Gersasp in southern France, and Aspidius (Aspapati, Asppat) in northern Spain, and of course the word Alan itself, which is still a very popular name in western Europe. Alans are credited for importing into western Europe their steppe tactics of warfare; these include never fighting on foot out of choice, having armour both for men and their mounts, and most significantly, the practice of tactical fake retreat; these Iranian steppe tactics were passed on to the Bretons, Visigoths and later, to the Normans, who used the fake retreat at many battles including the Battle of Hastings. Alans are also credited with teaching western Europeans the still popular sport of hunting on horseback with hunting dogs; a famous breed of medieval hunting dogs was called Alan (med. Latin Alanus) which, according to a 19th century authority on the history and origin of canine breeds, "derived originally from the Caucasus, whence it accompanied the fierce, fairhaired, and warlike Alani"; the town of Alano in Spain to this day bears two Alan dogs on its coat of arms.
1. Encyclopedia Iranica, "Alans" V. I. Abaev External link
2. Agusti Alemany, Sources on the Alans: A Critical Compilation. Brill Academic Publishers, 2000 ISBN 90-04-11442-4
3. For ethnogenesis, see Walter Pohl, "Conceptions of Ethnicity in Early Medieval Studies" Debating the Middle Ages: Issues and Readings, ed. Lester K. Little and Barbara H. Rosenwein, (Blackwell), 1998, pp 13-24)
Agusti Alemany, Sources on the Alans: A Critical Compilation. Brill Academic Publishers, 2000 ISBN 90-04-11442-4
Bernard S. Bachrach, A History of the Alans in the West, from their first appearance in the sources of classical antiquity through the early Middle Ages, University of Minnesota Press, 1973 ISBN 0-8166-0678-1
Bachrach, Bernard S. "The Origin of Armorican Chivalry." Technology and Culture, Vol. 10, No. 2. (Apr., 1969), pp. 166-171.
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Golb, Norman and Omeljan Pritsak, Khazarian Hebrew Documents of the Tenth Century. Ithaca: Cornell Univ. Press, 1982.
Hill, John E. 2003. "Annotated Translation of the Chapter on the Western Regions according to the Hou Hanshu." 2nd Draft Edition. 
Yu, Taishan. 2004. A History of the Relationships between the Western and Eastern Han, Wei, Jin, Northern and Southern Dynasties and the Western Regions. Sino-Platonic Papers No. 131 March 2004. Dept. of East Asian Languages and Civilizations, University of Pennsylvania.
Bernard S. Bachrach, A History of the Alans in the West