Do Thai numbers come from Cantonese?

A couple of weeks ago I was in Thailand bargaining for renting a motorbike, when the shop owner, to conclude the negotiation, told me the price in Thai. I had just learnt the numbers in Cantonese, and I was surprisingly able to understand. First, I thought she was actually a Cantonese migrant, but some days later, talking to other locals, I realised that Thai numbers were astonishingly similar to Cantonese. Thai is not a Chinese language (a Sino-Tibetan language), so the similarity seemed natural to think of it as a result of trade and cultural influence. But a quick look to the map of the extension of Thai’s language family, Tai-Kadai, is enough to realize that an important part of Thai speakers lived in territories that are today part of China (Image 1), which explains the extensive influence from Chinese. 

Image (1)

Moreover, this area in Southern China hosts many speakers from the linguistic group where Cantonese belongs, the Yue subfamily of Sinitic languages (Image 2).

(Image 2): Sinitic languages in Southern China

Nevertheless, Thai numbers are not written in Chinese nor Arabic numerals, but they use the Hindu-Arabic numeral system (Table 1). It is interesting to notice how Thai numerals were borrowed orally, while both languages employed the writing systems of their respective traditions.

(Table 1): Comparison of Arabic, Hindu-Arabic and Chinese numerals

So what Southern Sinitic language gave Thai its numerals? Was it Southern Min (aka Min Nan), Hakka, or a Yue language such as Cantonese or Taishanese? In fact none of them. The contact predates indeed these languages. Most numerals were borrowed from Middle Chinese, and one of them, number 5, was possible even earlier, and borrowed from Old Chinese. Only number 1 comes from Proto-thai, while 0 is borrowed from Sanskrit. And why do Thai numbers sound like Cantonese today? Well, probably because Cantonese is one of the Sinitic languages that has phonetically evolved less from Middle Chinese. This is something you can notice when reading poems from Tang and Song dynasty (618 - 907 and 960 - 1279 AD respectively), where the ending words rhyme when read aloud in Cantonese but not in Mandarin.

Why would Cantonese rhyme more often than Mandarin in Middle Chinese poetry? Well, the short answer is that Cantonese did not experience as many sound changes as Mandarin. More precisely, Cantonese preserves one feature of Middle Chinese that is lost in its evolution into Mandarin: the so-called entering tone.

Middle Chinese is characterised by 4 tones:

1. 平 píng level
2. 上 shǎng rising
3. 去 qù departing
4. 入 rù entering

The first three tones can be easily mapped into Mandarin

• 平 píng level     > Mandarin Tones 1 & 2, depending on the initial consonant
• 上 shǎng rising > Mandarin Tones 3 & 4, depending on the initial consonant
• 去 qù departing > Mandarin Tone 4

Middle Chinese’s entering tone is characterised, apart from its specific pitch, by the presence of a final stop consonant: -p, -t, or -k. The evolution of syllables having this tone seems irregular in Mandarin, evolving into various other tones, often in unpredictable patterns. An illustrative example can be found in the poem 中秋見月聯句 “Watching the Mid-Autumn Moon”, where the rhymes of the final triplet are better rhymed when read in Cantonese. Although the Cantonese reading does not result in an exact rhyme, it is enough to note that these words used to rhyme in Middle Chinese. Compare to the so-different Mandarin counterparts:

Character	Meaning	Middle Chinese	Cantonese	Mandarin
桌	table	ʈaɨwk̚	coek3	zhuō
覺	be aware	kaɨwk̚	gok3	jué
邈	distant	maɨwk̚	mok6	miǎo

You can read the full poem here:

中秋見月聯句	Watching the Mid-Autumn Moon
(裴度) 莫辭終夜看，動致隔年期。	Pei Du: Do not begrudge watching the moon the whole night through, For once it passes, we must wait another year’s cycle.
(劉禹錫) 萬里清光滿，三更皓露垂。	Liu Yuxi: For ten thousand miles, the pure light is full and brimming, At the third watch of the night, the bright dew hangs heavy.
(張籍) 穴流猶可辨，蕙歇委成滋。	Zhang Ji: The streams flowing from mountain caves can still be discerned, The scent of the orchids has faded, left to wither in the damp.
(裴度) 湛露委干荷，輕飆亂疏桌。	Pei Du: Heavy dew settles upon the dried lotus leaves, A light whirlwind tosses the scattered oars.
(劉禹錫) 寥寥霽華潔，皛皛清輝覺。	Liu Yuxi: Vast and silent, the rain-cleared splendor is pure, Shining white, the clear radiance is felt.
(張籍) 縹緲疑可攀，夐絕終難邈。	Zhang Ji: Mist-wreathed and ethereal, one wonders if it can be climbed, But it is utterly secluded—forever distant and remote.