<span> As far as the land and agriculture is concerned some post-1980 studies indicate that food production was largely indigenous to the Indus Valley suggesting that the land was quite fertile. It is known that the people of Mehrgarh used domesticated wheats and barley,[46] and the major cultivated cereal crop was naked six-row barley, a crop derived from two-row barley (see Shaffer and Liechtenstein 1995, 1999). Archaeologist Jim G. Shaffer (1999: 245) writes that the Mehrgarh site "demonstrates that food production was an indigenous South Asian phenomenon" and that the data support interpretation of "the prehistoric urbanization and complex social organization in South Asia as based on indigenous, but not isolated, cultural developments." Others, such as Dorian Fuller, however, indicate that it took some 2000 years before Middle Eastern wheat was acclimatised to South Asian conditions.</span>
Please give a time frame for this question but I will still say that the answer is: <span>The major cause of the growth of the workforce was an increase in immigrants.</span>
Islamic doctors developed new techniques in medicine, dissection, surgery and pharmacology. They founded the first hospitals, introduced physician training and wrote encyclopaedias of medical knowledge
