While the introduction of vines to the Indian subcontinent came from Persia in around 500 BC there is no evidence to suggest that commercial viticulture existed before the 19th century. However, it was not until the 1980s that vineyards began to develop in any significant way. Having said this, even then, strict religious views on alcohol consumption, along with the stance taken by the government on prohibition still prevented India’s wine industry from growing exponentially. Nevertheless, in the last 20 years India’s wine production has grown year-on-year at a rate of 20% with international demand now at an all-time high. Today, there is approximately 125,000 acres of land in India given over to grape-growing. This produces 1.7 million tonnes of grapes per year, however only around 10% of this is used in wine production; the majority of grapes grown in India are grown for eating as table grapes or for raisins. The majority of India's wine regions are concentrated in the southern part of the country, most notably in Maharashtra and in Karnataka. With blistering high summer temperatures that can reach over 116°F (47°C) followed by heavy rainfall during monsoon season, vines have to cope with an extremely short growing season. These tropical conditions and climatic extremes mean that India’s winegrowers have to be careful to protect vines from sunburn, fungal diseases and over-ripeness. International grape varieties grown in India include, Cabernet Sauvignon, Shiraz, Merlot and Zinfandel and Chardonnay, Chenin Blanc, Clairette and Sauvignon Blanc.