Why do you suppose the ceramic army was deployed outside the tomb of Qin Shihuangdi and not in it?

Please read the section 3.2.2 entitled “The Qin Dynasty (221-206) and the Rise of Imperial China.” Also review a”Closer Look – The Tomb of Qin Shihuangdi” on page 100-111.
Why do you suppose the ceramic army was deployed outside the tomb of Qin Shihuangdi and not in it?