Complex sentence: IMPLAST is a unique Indian event, which by now is an important international event held regularly in India and countries across the world, including Australia (2000), Germany (2007) and the USA (2010).
Split into simpler sentences: IMPLAST is a unique Indian event, which by now is an important international event held with regular periodicity in India and countries across the world. This Indian event has been held in Australia (2000), Germany (2007) and USA (2010).