The introduction of Chinese tea plants, different from Indian tea, to India is commonly credited to Robert Fortune, who spent about two and a half years, from 1848 to 1851, in China working of behalf of the Royal Horticultural Society of London. Fortune employed many different means to steal tea plants and seedlings, which were regarded as property of the Chinese empire. He also used Nathaniel Bagshaw Ward's portable Wardian cases to sustain the plants. Using these small greenhouses, Fortune introduced 20,000 tea plants and seedlings to the Darjeeling region of India, on steep slopes in the foothills of the Himalayas, with the acid soil liked by Camellia plants. He also brought a group of trained Chinese tea workers who would facilitate the production of tea leaves. With the exception of a few plants which survived in established Indian gardens, most of the Chinese tea plants Fortune introduced to India perished. The technology and knowledge that was brought over from China was instrumental in the later flourishing of the Indian tea industry using Chinese varieties, especially Darjeeling tea, which continues to use Chinese strains.