Eric Hutton's Introduction to his Xunzi translation says, in part:
"Without a doubt, the Xunzi is one of the most philosophically interesting and sophisticated texts in the Confucian tradition. It covers a wide variety of topics—education, ritual, music, language, psychology, history, religion, ethics, politics, and warfare, to name just a few— and it provides quite thoughtful treatments of all these subjects. Indeed, despite being a very old text, many of its insights still ring true in the present. It is thus a text that amply rewards study, and not only for those seeking to understand ancient Chinese views in particular, but also for anyone reflecting on these important aspects of human life in general. [...] Our received text was first compiled by Liu Xiang (77–6 BCE).
Although the Xunzi is a very rich text, study of the Xunzi was relatively neglected for many centuries in China, due in large part to the greater popularity of another early Confucian text with rival ideas, the Mencius (also called the Mengzi). As a result, the Xunzi was initially also rather neglected by many Western students of Chinese thought. Fortunately, this situation is slowly being rectified, and study of the Xunzi has begun to flourish again both inside and outside China in recent years."
Master Xun lived 2 or 3 hundred years after Confucius.