Of the eight different types of stupa, the present example belongs to the category of 'Complete Victory,' commemorating Buddha's extension of his lifespan through meditation. The four lower steps on the pedestal symbolize the four immeasurable attitudes: love, compassion, sharing in joy, and equanimity, on the path towards enlightenment.
For the type, compare a Zanabazar workshop example at the Museum of Fine Arts, Ulaanbaatar, see G. Bguin et al., Tresors de la Mongolie, XVIIe-XIXe sicles, 1993, cat. no. 7.