The Xianyou dialect has extremely extensive tone sandhi rules: in an utterance, only the last syllable pronounced is not affected by the rules.
The two-syllable tonal sandhi rules are shown in the table below (the rows give the first syllable's original citation tone, while the columns give the citation tone of the second syllable):
Tone sandhi of the first syllable
dark level 544
light level 24
rising 332
dark departing 52
light departing 21
dark entering ʔ2
light entering ʔ4
dark level 544
24
22
24
22
light level 24
22
44
52
22
rising 332
24
44
24
dark departing 52
44
33
44
52
44
light departing 21
22
44
52
22
dark entering ʔ2
ʔ4
light entering ʔ4
ʔ2
ʔ4
ʔ2
Notes
^Min is believed to have split from Old Chinese, rather than Middle Chinese like other varieties of Chinese.[1][2][3]
References
^Mei, Tsu-lin (1970), "Tones and prosody in Middle Chinese and the origin of the rising tone", Harvard Journal of Asiatic Studies, 30: 86–110, doi:10.2307/2718766, JSTOR2718766