Until the late nineteenth century, Telok Ayer Street was the main commercial and residential thoroughfare in Singapore. As immigration from China increased, so did the adverse qualities usually associated with a highly concentrated population. Between the 1850s and the 1870s, the road was the centre of the notorious Chinese slave trade. By the turn of the century, the area had become polluted and congested, and these factors, as well as the increasing affluence of some of the merchants, were possibly the main reasons which drove them out of town to look for a more salubrious environment.