Complex sentence: Thiruvalluvar is thought to have lived sometime between the 2nd century BC and the 8th century AD, based on linguistic analysis of his writings, as there is no archeological evidence for when he lived.
Split into simpler sentences: Thiruvalluvar is thought to have lived sometime between the 2nd century BC and the 8th century AD. This estimate is based on linguistic analysis of his writings, as there is no archeological evidence for when he lived.