CREATE TABLE table_36940 ("Province" TEXT, "Prefecture" TEXT, "County" TEXT, "Tujia Population" FLOAT, "% of China's Tujia Population" TEXT)

Which province has a prefecture of Xiangxi with 0.81% of China's Tujia population?
SELECT "Province" FROM table_36940 WHERE "Prefecture" = 'xiangxi' AND "% of China's Tujia Population" = '0.81%'
SELECT "Province" FROM "table_36940" WHERE "% of China's Tujia Population" = '0.81%' AND "Prefecture" = 'xiangxi'