What international trade theory (or theories) best explain the rise of India as a major exporter of pharmaceuticals?

One of the great success stories in international trade in recent years has been the strong growth of India's pharmaceutical industry. The country used to be known for producing cheap knockoffs of patented drugs discovered by Western and Japanese pharmaceutical companies. This made the industry something of an international pariah. Because they made copies of patented products, and therefore violated intellectual property rights, Indian companies were not allowed to sell these products in developed markets. With no assurance that their intellectual property would be protected, foreign drug companies refused to invest in, partner with, or buy from their Indian counterparts, further limiting the business opportunities of Indian companies. In developed markets such as the United States, the best that Indian companies could do was to sell low-cost generic pharmaceuticals (generic pharmaceuticals arc products whose patents have expired).