I would like to add that the tannery is representative of two themes central to the novel - change and colonialism.

The tannery completely changes the peasants' way of life.  Until its coming they had lived a quiet existence dependent on the land, but the tannery introduces all the complications of urban living, literally transforming an age-old culture.  The work in the tannery is done by the Indian people, but the bosses are white men, forming a colonial hierarchy.  As Ruku says, "...they may live in our midst but I can never accept them, for they lay their hands upon us and we are all turned from tilling to barter, and hoard our silver since we cannot spend it, and see our children go without the food that their children gorge..." (Chapter 4).

It is because the tannery buys the land Nathan and Ruku depend upon for their livelihood that the two are left homeless and forced to embark on their fateful journey to seek a home with their son Murugan.