The term south caucasian is a geographic and a linguistic one.South caucasians are the hittites,mittani people,people from Urartu(today Armenia)and indians from Gange.The hittite language is almost identical whit old sanskrite.The Kurgan culture north of Caucas mountans seems to be the birth place of schitian ethnic group.This group apear arheologic in 5500BC,so is relative contemporane whit aryans(who apear in the same time in south of Caucas mountains).Iranic group of skitians,thracian,persian is not a new indoeuropean group like many belive, but it have same age as aryans.
Are 5 major theories about the original land of aryans :
1-the Max Muller theory who place the first aryans in Central Asia in today Thadjikistan or Afganistan(base on similar names of rivers and places in afganistan and names of rivers and places from rg veda)or in today Ukraine(base on kurgan culture).
2-in carpatian area(romania)base also on similar names of rivers,towns,mountains and the names of ones of Rg Veda and Mahabharata(this theory is postulate by english and american researchers from Cambrige,also by Napoleon Savescu).
3-from Indus Valley culture(Mohenjo Daro) they spread around in Central Asia and Europe(postulate by some indian and brahmin researchers).
4-aryans already exist in Ganga plain in the time of nonaryan Indus civilisation(2900-1700bc),but their material culture was not develop until 1500bc when they became liders in spreading indoeuropean religion and language around the world(this theory have few suporters iven in India).
5-the anatolian(Turkey and South Caucase)theory postulate that a aryan group from Mitani(relatives of hittites and urartu) defeted by assirians around 1800BC,move eastward pass through Indus Valley(peacefull or conflictual whit the local population)and setlled in Ganga Valley.
The hittites
Hittite language is the oldest indoeuropean language discovered.
The hittites was the first people who use iron as a common metal(for agricultural tooles and weapons),they are the first people who replace the bronze whit the iron.
In Armenia was discovered a metalurgic factory 7000 years old.Here was prelucrate objects of iron(steel),aluminium(rediscovered in 19century),cuper,magnesium and other metals.The workers use a bandage covering the mouth.
Hittites was having the most advance language in the world at that time.The religious hittite prayers have an elevate language ,fact for which we speak not only about a mithology(like in the case of sumerians,assirians and egiptians)but also about a theology-hittite theology.In this case the hittites are the first theologians of the world.The hittite texts,persian Avesta and Vedas are from the same family of tinking.Hittites(2500-1200BC) indirectly influence the first greek philosophers(700BC)and the first indian philosophers(900BC).Also greeks(in 400BC) and indians(in 50AD)was the first that completly develope the art(are 3 stages of art

rimitive,intermediar,complete).Hittites&Co was agricultores,seminomadic and nomadic people.
The thracian was the most numerous people after indians(Herodot say),living in today Turkey,north Greece,Bulgaria,east Serbia,Romania,west Ukraine,Cehia,Slovacia.Was divided in 200 tribes(messi,bessi,phrigians,abioi,boii,getae,and other 194 tribes).They are the aliates of Troi against greeks,and they destroy the hittites in 1200BC.
The gene M 173 is the iranic gene.This gene is spread among east europeans,central asia and north west india .
Is not such thing as pure rase but dominand gene.
The term aryan is a social one(aryan=nobil)but today is use like a ethnic term;indoeuropean(or euroindian)is a more better term but is to long.
If the rase is base on skin color then are only 2 rases temperate rase(white)and tropical rase(black).In this case the northen chinese(white)are a diferent rase then chinese from south china(black).In reality the rase is base on morphologic structure of the body.And we have 3 rase:caucasian(black or white)-european,turkish,indian,finnic,semitic;mongoloid(black or white)-chinese,indonesian,amerindian,polinesian;afroide(in general black)-african,australian aborigen,melanesian.Inreality exist only 1 rase,the human rase.