Xu is a Mandarin pinyin spelling shared by distinct Chinese surnames, including 徐 (Xú) and 許/许 (Xǔ). The character 徐 has the ordinary meaning “slowly”; 許 has senses including “permit” or “agree.” Those translations do not explain every family's surname history: both names have traditions connecting them to ancient states, and the unmarked spelling Xu conceals their different characters and tones. Compare the Ministry of Education entries for 徐 and 許.
徐 (Xú): A Character and an Ancient State
Taiwan's Ministry of Education dictionary reads 徐 as xú, with Mandarin's second tone. It distinguishes the adverb meaning “slowly,” the name of an ancient state, and the surname. It places the state's former site approximately north of present-day Sixian in Anhui and records its destruction by Wu. These separate definitions matter: a surname associated with a state should not automatically be interpreted as a nickname describing a slow-moving ancestor. Ministry of Education, “徐”.
The Dictionary of American Family Names connects one 徐 tradition with the state of Xu in the Jiangsu–Anhui area, whose name became a surname after annexation by Wu in 512 BC. It also records a Shang-descended Xu clan transferred to Lu and a Xu family among the Di people of northern China. These accounts describe more than one historical route. Hanks, Lenarčič, and McClure, “Xu,” sense 1.
The annexation date belongs to the dictionary's account of the state. It is not a dated birth certificate for the surname, nor evidence that every subsequent 徐 household descends from a single refugee family.
許/许 (Xǔ): A Different State and Surname
許, written 许 in simplified Chinese, is read xǔ, with Mandarin's third tone. It is not a simplified spelling of 徐. The Ministry of Education dictionary separates its verbal meanings, including agreeing or giving permission, from the ancient state and surname. It locates that state near Xuchang in Henan and says it was destroyed by Chu. It also gives the Han scholar Xu Shen (許慎) as an example of the surname's use. Ministry of Education, “許”.
The surname dictionary traces one 許 tradition to a state granted to Wen Shu under King Wu of Zhou; its name was reportedly retained as a surname after conquest by Chu. A separate account claims descent from Xu You, associated with the legendary Emperor Yao. The latter is a legendary descent tradition, not a verified pedigree for modern bearers. Hanks, Lenarčič, and McClure, “Xu,” sense 2.
A historical individual such as Xu Shen establishes surname usage in a particular historical setting. Connecting that individual to a living family would require evidence across the intervening generations. Neither the character's meaning nor an ancestral story supplies those missing links.
Other Surnames Written Xu
The surname dictionary also includes 胥, 續, and 須 under Xu. Its explanations include a personal-name source for 胥, a fief-name source for 續, and a shortened state-name source for 須. These are separate Chinese names, not interchangeable spellings of 徐 or 許. Hanks, Lenarčič, and McClure, “Xu,” senses 3–5.
For a record containing only Latin letters, leave the character unidentified until another document supplies it. Selecting 徐 simply because it seems familiar can send a search into the wrong surname's records.
Xu, Hsü, and Hsu in Records
The 2006 reference index The hundred surnames lists Hsü as the Wade–Giles counterpart of pinyin Xu for several different characters. Its separate Xu rows demonstrate why conversion between romanization systems does not identify a unique surname. The Indexer, vol. 25, no. 2, centrepiece p. C7.
The Dictionary of American Family Names explicitly records Hsu as an alternative Mandarin romanization of 徐, 許, 胥, 續, and 須. Its Hsu entry also includes possible connections to Su and Shu, so Hsu cannot safely be converted to Xu in every case. Read the Hsu dictionary entry reproduced by Geneanet.
A change from Hsu to Xu can therefore reflect a change in how a Chinese name is written in Latin letters. It need not mean that the family adopted a different Chinese surname. Preserve each document's spelling, then test a proposed connection using the full name, original character, relatives, dates, and places. Our guide to testing related surname spellings explains how to separate a search possibility from an established identification.
Wang offers a useful comparison because it also conceals distinct characters when tones are omitted. It is a comparison of naming problems, not a related form of Xu. The East Asian origin guide provides broader Chinese naming context.
Researching a Xu Family
Begin with the most recent securely identified relative and work backward. For this surname, recovering the written Chinese name is often more useful than collecting additional matches for the letters Xu.
1. Find the character in a family document. Look for Chinese writing on certificates, letters, gravestones, or family records. Keep a photograph of the original alongside a transcription; do not rely solely on an indexer's romanization. If it is 許 or 许, record both forms for searching. 2. Build a spelling trail. Search Xu, Hsu, and Hsü where the record system permits, but keep candidates separate until their biographical details agree. Note the language and place of issue rather than assuming a spelling proves a birthplace or nationality. 3. Identify a locality more precisely than “China.” Seek a village, county, or former address in documents tied to the known person. The ancient states in surname explanations are not substitutes for the family's documented home. A Xu genealogy from the right province is still only a candidate without a connection to the right household. 4. Evaluate any family genealogy at the point of connection. Record its title, compilation date, locality, and the generation naming the known ancestor. Compare spouses, children, dates, and residences against independent records where available. Treat an ancient founding account separately from the recent generations you can verify. 5. Follow the migration route into the appropriate archive. For a United States branch, the National Archives' Chinese Heritage guide links to immigration records, Chinese Exclusion Act case files, and regional finding aids. Use the relevant port and period to narrow the search; a name appearing in an index is a lead to a file, not a complete family history. National Archives, Chinese Heritage.
Keep unresolved character identifications and spelling connections visible in your notes. The surname evidence checklist can help distinguish what a document actually says from what you infer. Shared spelling or even a shared Chinese character does not by itself establish kinship, ethnicity, or descent from an ancient ruler.
References
- Patrick Hanks, Simon Lenarčič, and Peter McClure, eds. Dictionary of American Family Names, 2nd ed. Oxford University Press, 2022. Entries Xu, senses 1–5, reproduced by Ancestry, and Hsu, reproduced by Geneanet.
- Ministry of Education, Taiwan. Revised Mandarin Chinese Dictionary, 2021 online edition. Entries 徐, xú and 許, xǔ.
- The Indexer. “The hundred surnames: a Pinyin index.” Vol. 25, no. 2, October 2006, centrepiece pp. C3–C8, especially the Xu rows on p. C7. Reference index.
- U.S. National Archives and Records Administration. “Chinese Heritage,” last reviewed June 2, 2020. Research guide and archival finding aids.