The BSE benchmark index Sensex was trading 221 points up at 18,783 a short while ago. It gained nearly 161 points in early trade on sustained buying by funds and retailers amid a firming trend in the Asian region. The 30-share barometer had gained over 130 points in the previous two sessions.The wide-based National Stock Exchange index Nifty was also trading 62 points up at 5,707 a short while ago.