[4] In a paper presented to the first International Congress of Linguists in 1928, he used a German calque of this term, Sprachbund, defining it as a group of languages with similarities in syntax, morphological structure, cultural vocabulary and sound systems, but without systematic sound correspondences, shared basic morphology or shared basic vocabulary.
[8][9][10] A rigorous set of principles for what evidence is valid for establishing a linguistic area has been presented by Campbell, Kaufman, and Smith-Stark.
[11] The idea of areal convergence is commonly attributed to Jernej Kopitar's description in 1830 of Albanian, Bulgarian and Romanian as giving the impression of "nur eine Sprachform ... mit dreierlei Sprachmaterie" (lit.
[15] In a classic 1956 paper titled "India as a Linguistic Area", Murray Emeneau laid the groundwork for the general acceptance of the concept of a sprachbund.
[9][17][18] Some linguists, such as Matthias Castrén, G. J. Ramstedt, Nicholas Poppe and Pentti Aalto, supported the idea that the Mongolic, Turkic, and Tungusic families of Asia (and some small parts of Europe) have a common ancestry, in a controversial group they call Altaic.
[citation needed] Koreanic and Japonic languages, which are also hypothetically related according to some scholars like William George Aston, Shōsaburō Kanazawa, Samuel Martin and Sergei Starostin, are sometimes included as part of the purported Altaic family.
[citation needed] A common alternative explanation for similarities among the "Altaic" languages, such as vowel harmony and agglutination, is that they are due to areal diffusion.
[citation needed] Standard Average European (SAE) is a concept introduced in 1939 by Benjamin Whorf to group the modern Indo-European languages of Europe which shared common features.
Whorf likely considered Romance and West Germanic to form the core of the SAE, i.e. the literary languages of Europe which have seen substantial cultural influence from Latin during the medieval period.
The Standard Average European Sprachbund is most likely the result of ongoing language contact in the time of the Migration Period[22][full citation needed] and later, continuing during the Middle Ages and the Renaissance.