In English, the term ‘Chinese’ is commonly used to refer to the standard language of the People’s Republic of China, as well as one of the official languages of Singapore, i.e., Standard Mandarin Chinese (henceforth: SMC), also known in China as 普通话 Pǔtōnghuà (lit. ‘common language’). However, ‘Chinese’ can also be used to refer, more generally, to any variety belonging to the Sinitic branch of the Sino-Tibetan language family (see, e.g., ^[1][2][1,2]). In the Chinese tradition, as well as in much of the international literature on China and its language situation, it is customary to refer to Sinitic languages other than SMC as ‘dialects’ (方言 fāngyán). This is mostly due to the fact that these varieties are not officially recognized as languages, at least in Mainland China, nor did they undergo a process of standardization (with the partial exception of Cantonese; see, e.g., [3]). Also, in the Chinese context, the idea of having only one ‘language’ is seen as a symbol of national unity, and as a marker of ethnic identity [4]. Thus, the labels ‘Sinitic languages’, ‘Chinese languages’, and (somewhat paradoxically) ‘(the) Chinese language’ are all used to refer to the same group of varieties.

The idea of ‘Chinese’ as a unitary language with regional variation, somewhat similarly to English, was famously captured in Yuen Ren Chao’s idea of a ‘universal Chinese grammar’ [5] (p. 13):

Chao can be considered “the founder of modern Chinese Linguistics”, and his views of Chinese/Sinitic have indeed been very influential in the field [6] (p. 217). However, Chao’s idea of a fundamentally shared grammar among all Sinitic languages (or, as he puts it, “dialects of the Chinese language”) has now been conclusively proven to be highly misleading. A rich and growing body of research has indeed shown that the so-called Chinese ‘dialects’ are at least as diverse as, e.g., Romance or Germanic languages, or even more, and that their differences are not limited to the phonological and lexical components, but also involve, to a very significant extent, their grammar ^[6][7][8][6,7,8]. Besides the above-mentioned factors related to language ideology, another reason for this common misconception concerning Sinitic grammar is that, very often, in Chinese dialects, it is possible to create ‘hybrid’ structures, making use of SMC grammar, but dialect phonology and even lexicon (a phenomenon known as ‘ditaxia’ [9]). See the following Cantonese examples (adapted from [9], p. 1277; in this article, the glosses follow the general guidelines of the Leipzig Glossing Rules):

(1)	a.	我	比	佢
‘I am taller than her/him’

In (1), we see two possible comparative constructions of Cantonese. (1a), based on the marker 比 bei2 ‘compare’, follows the ‘marker–standard–adjective’ order. (1b), on the other hand, makes use of the marker 過 gwo3 ‘surpass’, and shows the ‘adjective–marker–standard’ order. The latter is the ‘authentic’, colloquial comparative construction for Cantonese, while (1a) belongs to the formal register, and it is more often used by educated speakers [9]. What is crucial here is that (1a), the formal variant, closely corresponds to the ‘standard’ SMC comparative construction:

(2)	我	比	他	高
	wǒ	bǐ	tā	gāo
	1sg	compare	3sg	tall
	‘I am taller than him’

高
		ngo5	bei2	keoi5	gou1
		1sg	compare	3sg	tall
	b.	我	高過	佢
		ngo5	gou1-gwo3	keoi5
		1sg	tall-surpass	3sg

If we look at the formal register of Cantonese, one might be led to believe that the same constructions of SMC grammar can indeed be used in other Sinitic varieties, with differences mostly limited to the phonological and lexical level; however, this is obviously not true if we look at the informal, colloquial register of dialects [6].

Thus, as pointed out by Norman [1] (p. 72), for the purposes of cross-linguistic comparison, “Chinese is a vast dialectal complex containing hundreds of mutually unintelligible local varieties, each of which can be viewed as a distinct object […]”. In this article, we use ‘Sinitic language(s)’ and ‘Chinese dialect(s)’ interchangeably, as they normally describe the same entities.

The most recent, generally accepted genealogical classification of Sinitic languages includes ten groups [10], which are sometimes erroneously labeled as ‘languages’ [1]: namely, Mandarin, Jin, Wu, Gan, Xiang, Hui, Hakka, Yue, Min, and Pinghua, plus some unclassified languages. An earlier partition, which still enjoys some degree of acceptance, includes only seven groups, to the exclusion of Jin, Hui, and Pinghua [11]. Each group is then further divided into several levels of subgrouping, down to the individual varieties (see [4] for details). Since SMC is based on Mandarin dialects, from a historical point-of-view, other Chinese dialects should be seen as sister languages of SMC [11]. This widely applied classification, however, is almost exclusively based on phonological criteria. Chiefly, the evolution of Middle Chinese voiced obstruents [12], as the phonological system of all modern dialects (except the Min group) can be understood as the evolution of that of Middle Chinese, at least in the traditional approach to Chinese historical linguistics (but see [13]). This type of ‘family tree’ approach to dialect classification can represent only groupings justified on the basis of vertical transmission, while the evolution of Sinitic languages has been strongly shaped by contact, both within the family and with non-Sinitic languages ^[14][15][14,15] (we shall get back to this below); also, a phonology-based genealogical classification may not reflect differences in grammatical aspects ^[12][14][12,14].

Indeed, if we look at the typological features of modern Sinitic languages through the lens of their genealogical classification, we may notice that they appear as very different from the so-called ‘Tibeto-Burman’ languages (i.e., the non-Sinitic Sino-Tibetan languages; on the structure of the Sino-Tibetan family, see [16]). Sinitic languages are overwhelmingly tonal, verb-medial, and isolating/analytic, while Tibeto-Burman languages are not necessarily tonal, they are dominantly verb-final, and exhibit more varied (and elaborated) morphological profiles, including isolating languages like Karen, languages with transparent and regular agglutinative morphology (Lolo-Burmese, Tibetic, and Boro-Garo), and also paradigmatically complex languages, with elaborate argument indexation and transitivity management systems (Rgyalrongic, Kiranti) [17]. The divergence between Sinitic and the rest of the Sino-Tibetan family has been attributed, at least partly, to contact. At least since the Qin period (221–207 BCE), speakers of Sinitic migrated repeatedly from the Central Plains region to (what is now) Southern China, leading to contact with the so-called 百越 Bǎi Yuè (lit. ‘Hundred Yue’) ethnic groups inhabiting the region, who were likely speakers of Hmong-Mien, Tai-Kadai, and Austroasiatic languages ^[15][18][15,18]. This arguably led to the convergence of Sinitic and the Mainland Southeast Asian language type, characterized, e.g., by the use of lexical tone, isolating/analytic morphology, lack of agreement, verb medial basic constituent order, among other features ^[19][20][19,20] (we will get back to this in Section 2). However, Mainland Southeast Asian traits are actually more common in the Sinitic languages of Southern China. This is because Northern China was a site for contact with speakers of ‘Altaic’-type languages, belonging to the Mongolic, Turkic, and Tungusic languages ^[15][20][15,20], leading to the development of some typological features shared with languages of the Northern Asian region [21]. This is commonly referred to as the ‘Altaicization’ of Northern Sinitic, as opposed to the ‘Taiization’ of Southern Sinitic [22]. In addition, as mentioned above, internal migration of Chinese-speaking people led to contact, admixture, patterns of areal diffusion and convergence among Sinitic varieties, cross-cutting genealogical subdivisions (see below, Section 5).

This article is organized as follows. In Section 2, we provide a general overview of the main typological characteristics of Sinitic. In Section 3 and Section 4, we discuss, respectively, morphological and syntactic aspects, while in Section 5, we focus on the areal patterns of distribution of typological features. In Section 6, we offer our concluding remarks, as well as some hints on the future prospects of this field of inquiry.