The benchmark BSE Sensex rose by 56 points to 21,157 in early trade today on sustained buying by funds amid a firm trend on other Asian bourses.The wide-based Nifty of the National Stock Exchange moved up by 16 points to 6,301.In other Asian markets, Hong Kong's Hang Seng rose by 1 per cent, while Japan's Nikkei was up by 0.79 per cent in early trade today.The US Dow Jones Industrial Average gained 0.45 per cent to close at another new high in yesterday's trade.