China and India are the most populous countries on the planet. Formerly communistic, China turned very capitalistic. This large country and great culture offers many superb touristy sites with the Great Wall (the only structure visible from the moon) and the Terra Cotta Warriors being the most famous. Beijing, Shanghai, Guilin and Xian in particular are worth a visit. China has excellent, very fast trains and travel has become really easy.
Hong Kong and Taiwan are listed separately.