called R1b1a1b-CTS3187). According to the diversification of Z93 and the "early urbanization within the Indus Valley ... occurred at [5,600 years ago] and the geographic distribution of R1a-M780 (Figure 3d) may reflect this." note that "striking expansions" occurred within R1a-Z93 at c. 4,500–4,000 years ago, which "predates by a few centuries the collapse of the Indus Valley Civilisation." However, according to , steppe pastoralists are a likely source for R1a in India. Phylogeny The R1a family tree now has three major levels of branching, with the largest number of defined subclades within the dominant and best known branch, R1a1a (which will be found with various names such as "R1a1" in relatively recent but not the latest literature). Topology The topology of R1a is as follows (codes [in brackets] non-isogg codes): Tatiana et al. (2014) "rapid diversification process of K-M526 likely occurred in Southeast Asia, with subsequent westward expansions of the ancestors of haplogroups R and Q." P P295/PF5866/S8 (also known as K2b2). R (R-M207) R* R1 (R-M173) R1* R1a (M420) (Eastern Europe, Asia) R1a* R1a1 (M459/PF6235, SRY1532.2/SRY10831.2) R1a1 (M459) R1a1a (M17, M198) R1a1a1 (M417, page7) R1a1a1a (CTS7083/L664/S298) R1a1a1b (S224/Z645, S441/Z647) R1a1a1b1 (PF6217/S339/Z283) R1a1a1b1a (Z282) [R1a1a1a*] (Z282) R1a1a1b1a1 [The old topological code is R1a1a1b*，which is outdated and might lead to some confusion.] (M458) [R1a1a1g] (M458) [R1a1a1g*] [R1a1a1g1] (M334) R1a1a1b1a1a (L260/S222) [R1a1a1g2] R1a1a1b1a2 (S466/Z280, S204/Z91) R1a1a1b1a2a R1a1a1b1a2b (CTS1211) [R1a1a1c*] (M558) [R-CTS1211] (V2803/CTS3607/S3363/M558, CTS1211/S3357, Y34/FGC36457) R1a1a1b1a2b3* (M417+, Z645+, Z283+, Z282+, Z280+, CTS1211+, CTS3402, Y33+, CTS3318+, Y2613+) (Gwozdz's Cluster K) R1a1a1b1a2b3a (L365/S468) R1a1a1b1a3 (Z284) [R1a1a1a1] (Z284) R1a1a1b2 (F992/S202/Z93) [R1a1a2*] (Z93, M746) R1a1a1b2a (F3105/S340/Z94, L342.2/S278.2) [R1a1b2a*] (Z95) R-Z94 (Z94/F3105/S340, Z95/F3568) R-Z2124 (Z2121/S3410, Z2124) [R1a1b2a*] (Z2125) [R1a1b2a*] (M434) [R1a1a1f] (M434) [R1a1b2a*] (M204) [R1a1b2a1*] (M560) [R1a1b2a2*] (M780, L657) (India) [R1a1b2a3*] (Z2122, M582) [R1a1a1c] (M64.2, M87, M204) [R1a1a1d] (P98) [R1a1a1d2a] [R1a1a1e] (PK5) R1b (M343) (Western Europe) R2 (India) Haplogroup R R-M173 (R1) R1a is distinguished by several unique markers, including the M420 mutation. It is a subclade of Haplogroup R-M173 (previously called R1). R1a has the sister-subclades Haplogroup R1b-M343, and the paragroup R-M173*. R-M420 (R1a) R-M420, defined by the mutation M420, has two branches: R-SRY1532.2, defined by the mutation SRY1532.2, which makes up the vast majority; and R-M420*, the paragroup, defined as M420 positive but SRY1532.2 negative. (In the 2002 scheme, this SRY1532.2 negative minority was one part of the relatively rare group classified as the paragroup R1*.) Mutations understood to be equivalent to M420 include M449, M511,