for paper production, which lowered the cost of creating books, making them more prevalent and accessible to more people. As more texts began to be produced, a new market for book vendors opened, and libraries and bookstores appeared in the city. As the public and private sectors of the community became more educated, cultural narrative and secular writing began. In the city, demand for secular literature, designed for entertainment, developed, which shaped the culture of the city's population, as well as the Abbasid Empire as a whole, with Baghdad being their crowning achievement and reason for the Golden Age of Islam. At this time, Baghdad was revered as the "center of the world" because of its scholarship. Michael Cooperson says that "Baghdadi scholars were so numerous and so eminent that reference to them could continue to support the 'center of the world' thesis…". The influx of trade and commerce brought these scholars to the city and made it the cosmopolitan center of knowledge that it became. Al-Mansur's foundation and construction of the city as well were done by only the best and brightest scholars, further fostering the notion of a highly intellectual city population to support the Golden Age. At the height of the golden age in Baghdad, it was estimated that there were over one and half million people living in the city. Al-Mansur's foundation of the city was ultimately based on its potential position as a military arsenal, and its ability to house and support many troops. Large numbers of troops were what originally gave the city such a dense population, but as the army continued to need supplies more people came to the city for jobs, thus being another reason Baghdad became a center of commerce. Baghdad also being named the new capital of the Abbasid caliphate drew in people for the prestige and name alone. Al-Mansur designated a governor of Baghdad and sent with him a number of elites who gave the city a higher status and poise, drawing more scholars to study in such a well-educated and cosmopolitan city. Baghdad grew and developed in a variety of facets, and because of this it may have became the largest city in the world during that time. Stagnation and invasions (10th to 16th centuries) By the 10th century, the city's population was between 300,000 and 500,000. Baghdad's early meteoric growth slowed due to troubles within the Caliphate,