The Classic of Mountains and Seas (Shānhǎi Jīng 山海經) is a compilation of mythological texts from well before the Hàn dynasty, i.e., from a period of time when the Chinese had a completely different set of religious sytems than in Imperial times — see p35-36 of The Celestial Empire.
As per the shamanic part of the archaic belief system, the sun was believed to rise from a gigantic mulberry tree in the far east, called the Leaning Mulberry (fúsāng 扶桑). This tree is obviously an axis mundi type of tree, common to all shamanic belief systems. The interesting difference here is that the fúsāng is supposed to be in the far eastern end of the world rather than at its centre.
It is interesting to note that the earliest versions of the myth mention ten suns, who would travel round the sky one after the other. This could be the origin of the ten heavenly stems.
One day, the ten suns all set out at once by mistake, threatening the burn the world. Hòuyì (后羿) the archer saved the day by shooting down all but one of the suns. Hòuyì is celebrated at the Mid-Autumn Festival, see p14 of TCE.