Why did Thai Language borrow Middle Chinese for numerals 2-4 (song, sam si), 7-10 (chet, pet, kao, sip), 20 (yi sip) & -1 (et, in higher numerals) whereas numerals 5 (ha < *lŋa / *sŋa) & 6 (hok < *krok ) seem to be Old Chinese loanwords?
Why did Thai Language borrow Middle Chinese for numerals 2-4 (song, sam, si), 7-10 (chet, pet, kao, sip), 20 (yi sip) & -1 (et, in higher numerals) whereas numerals 5 (ha < *lŋa / *sŋa) & 6