Complex sentence: In late 19th century and early 20th century, the Mahabalipuram site was largely a focus of colonial era tourist guides and speculations, parts of many monuments were covered with sand, and little was done to preserve the site.
Split into simpler sentences: In late 19th and early 20th centuries, the Mahabalipuram site was largely the focus of colonial era tourist guides and speculations. Parts of many monuments were covered with sand, and little was done to preserve the site.