Haplogroup D1 or D-M174 is a subclade of haplogroup D-CTS3946. This broad lineage of the male-specific portion of the human Y chromosome is found primarily in East Asia, Magar-ethnic Nepal and the Andaman Islands. It is also found regularly with lower frequency in Central Asia, North Asia and Mainland Southeast Asia, and, more rarely, in Europe and West Asia.

Human Y chromosome haplogroup D-M174 likely originated in Asia roughly 60,000 years ago. While haplogroup D-M174, along with haplogroup E, contains the distinctive YAP polymorphism—which indicates their closer ancestry than C—no haplogroup D-M174 chromosomes have been found outside of Asia. Haplogroup D1 is also often found in Southern Asia's populations.

Several studies (Hammer et al. 2006, Shinoda 2008, Matsumoto 2009) suggested that paternal haplogroup D-M174 originated in Central Asia.

A 2017 study by Mondal et al. finds that the Riang people (a Tibeto-Burmese population) and the Andamanese share the same D clade (D1a3, also known as D1a2b) and have their closest lineages with other clades in East Asia. The shared Jarawa and Onge D1a2b lineage dates back around 7,000 years ago. The East Asian D1a2b lineage diverged from the Japanese D1a2a lineage around 53,000 years ago. The authors conclude: "This strongly suggests that haplogroup D does not indicate a separate ancestry for Andamanese populations. Rather, haplogroup D was part of the standing variation carried by the Eastern OOA expansion, and later lost from most of the populations except in Andaman and partially in Japan and Tibet".

A 2019 study by Haber et al. argued that haplogroup D-M174 most likely diverged from haplogroup DE within Africa, and then participated in the expansion out of Africa with haplogroup C-M130 and haplogroup FT-M89.

A 2020 genetic study by Hallast et al. on ancient and modern haplogroups using a phylogenetic analysis of haplogroup C, D, and FT sequences—including very rare deep-rooting lineages such as D0/D2, a divergent D lineage not belonging to D-M174—argues that the initial splits within haplogroup CT (an ancestor of DE) occurred in Africa. It also argues that phylogeographic analyses of ancient and present-day non-African Y chromosomes all point to East/Southeast Asia as the origin of all known surviving non-African male lineages (apart from recent migrants) soon after an initial 70,000–55,000-year-ago migration from Africa of basal haplogroup D and other basal Y-lineages. It argues that these lineages then rapidly expanded across Eurasia, diversified in Southeast Asia, and expanded westward around 55,000–50,000 years ago, replacing other local lineages within Eurasia; haplogroup D (as D-M174) then underwent rapid expansions within Eastern Eurasian populations and consists of five branches that formed about 45,000 years ago. The study finds that these haplogroups currently have their greatest diversity in Eastern Eurasia (East/Southeast Asia).

Haplogroup D-M174 is found today with high frequency among populations in Tibet, Magar-ethnic Nepal, northern Myanmar, Qinghai, the Japanese archipelago, and the Andaman Islands, though curiously not as much in the rest of India. The Ainu people of Japan and various Tibeto-Burmese people (such as the Tripuri people) are notable for possessing almost exclusively haplogroup D-M174 chromosomes. Haplogroup D-M174 chromosomes are also found at low to moderate frequencies among the Bai, Dai, Han, Hui, Manchu, Miao, Tujia, Xibe, Yao, and Zhuang peoples of China and among several minority populations of Sichuan and Yunnan that speak Tibeto-Burman languages and reside in close proximity to the Tibetans, such as the Jingpo, Jino, Mosuo, Naxi, Pumi, Qiang, and Yi.

Haplogroup D is also found in populations in China proper and in Korea, but with much lower frequency than in Tibet and Japan. A study published in 2011 found D-M174 in 2.49% (43/1729) of Han Chinese males, with frequencies tending to be higher than average toward the north and west of the country (8.9% of Shaanxi Han, 5.9% of Gansu Han, 4.4% of Yunnan Han, 3.7% of Guangxi Han, 3.3% of Hunan Han, and 3.2% of Sichuan Han). In another study of Han Chinese Y-DNA published in 2011, haplogroup D-M174 was observed in 1.94% (7/361) of a sample of unrelated Han Chinese male volunteers at Fudan University in Shanghai, with the origins of most of the volunteers being traced back to East China (Jiangsu, Zhejiang, Shanghai, and Anhui).