Burma's annexation ushered in a new period of economic growth. The economic nature of society also changed dramatically. The British began exploiting the rich soil of the land around the Irrawaddy delta and cleared away the dense mangrove forests. Rice, which was in high demand in Europe, especially after the building of the Suez Canal in 1869, was the main export. To increase the production of rice, many Burmese migrated from the northern heartland to the delta, shifting the population concentration and changing the basis of wealth and power.