The global language system is the "ingenious pattern of connections between language groups". Dutch sociologist Abram de Swaan developed this theory in 2001 in his book Words of the World: The Global Language System and according to him, "the multilingual connections between language groups do not occur haphazardly, but, on the contrary, they constitute a surprisingly strong and efficient network that ties together – directly or indirectly – the six billion inhabitants of the earth." The global language system draws upon the world system theory to account for the relationships between the world's languages and divides them into a hierarchy consisting of four levels, namely the peripheral, central, supercentral and hypercentral languages.
According to de Swaan, the global language system has been constantly evolving since the time period of the early 'military-agrarian' regimes. Under these regimes, the rulers imposed their own language and so the first 'central' languages emerged, linking the peripheral languages of the agrarian communities via bilingual speakers to the language of the conquerors. Then was the formation of empires, which resulted in the next stage of integration of the world language system.
Firstly, Latin emerged from Rome. Under the rule of the Roman Empire, which ruled an extensive group of states, the usage of Latin stretched along the Mediterranean coast, the southern half of Europe, and more sparsely to the North and then into the Germanic and Celtic lands. Thus, Latin evolved to become a central language in Europe from 27 BC to 476 AD.
Secondly, there was the widespread usage of the pre-classical version of Han Chinese in contemporary China due to the unification of China in 221 BC by Qin Shi Huang.
Thirdly, Sanskrit started to become widely spoken in South Asia from the widespread teaching of Hinduism and Buddhism in South Asian countries.
Fourthly, the expansion of the Arabic empire also led to the increased usage of Arabic as a language in the Afro-Eurasian land mass.