The Sensex at the Bombay Stock Exchange regained the 21,000 level in early trade today, as it surged 100 points to 21,029 on heavy fund inflows in realty, banking and auto sectors, amid a firming trend in the Asian region. The 30-share index had gained 359 points in the previous session.The Nifty at the National Stock Exchange rose by 30 points to 6,251.In the Asian region, Japan's Nikkei gained 1.22 per cent, while Hong Kong's Hang Seng was up by 0.70 per cent in early trade today.The US Dow Jones Industrial Average rose 0.72 per cent to close at fresh all-time high in yesterday's trade.