|Born||15 October 1889|
|Died||20 October 1978 (aged 89)|
|Alma mater||Uppsala University|
|Known for||Pioneering reconstructions of Middle Chinese and Old Chinese|
|Fields||Ancient Chinese linguistics, literature|
|Institutions||Museum of Far Eastern Antiquities|
University of Gothenburg
|Academic advisors||Johan August Lundell|
|Notable students||Hans Bielenstein|
|Hanyu Pinyin||Gāo Běnhàn|
Klas Bernhard Johannes Karlgren (Swedish pronunciation: [ˈbæ̌ːɳaɖ ˈkɑ̂ːɭɡreːn]; 15 October 1889 – 20 October 1978) was a Swedish sinologist and linguist who pioneered the study of Chinese historical phonology using modern comparative methods. In the early 20th century, Karlgren conducted large surveys of the varieties of Chinese and studied historical information on rhyming in ancient Chinese poetry, then used them to create the first ever complete reconstructions of what is now called Middle Chinese and Old Chinese.
Bernhard Karlgren was born on 15 October 1889 in Jönköping, Sweden. His father, Johannes Karlgren, taught Latin, Greek, and Swedish at the local high school. Karlgren showed ability in linguistics from a young age, and was interested in Sweden's dialects and traditional folk stories. He mastered classical languages and was an accomplished translator of Greek poetry into his native language. He displayed an early interest in China, and wrote a drama, The White Hind, set in that country in his early teens. His first scholarly article, a phonetic transcription, based on a system devised by Johan August Lundell, of traditional folk stories from his native province of Småland, was completed when he was 14. and published in 1908 when he was only 18 years old. He studied Russian at Uppsala University under Johan August Lundell, a Slavicist interested in comparative linguistics. He graduated in 1909 with a bachelor's degree in Nordic, Greek, and Slavonic languages. Although he initially intended to specialize in the Scandinavian languages, on the advice of his elder brother Anton Karlgren (1882–1973) he decided to focus on Chinese instead, attracted to it also by the fact that, as Lundell had told him, Chinese contained a great number of dialects. He departed for St. Petersburg, which, under the guidance of Vasily Vasilyev, had created one of the major European centres for the study of Chinese. While there, Karlgren, studying under A. I. Ivanov, won a grant to study Chinese dialects, even though he had no background in Chinese at that point.
Karlgren lived in China from 1910 to 1912. He achieved basic fluency and literacy after only a few months of study, and prepared a questionnaire of 3,100 Chinese characters to gather information on Chinese dialects. After his grant money ran out, Karlgren supported himself by teaching French and, famously, English, which, according to one anecdote, he had never been taught but had picked up from English-speaking passengers on the ship from Europe to China. In fact he had received a high credit in English in his final High School exams. He eventually gathered data on 19 different Mandarin dialects, as well as Shanghainese, the Fuzhou dialect of Eastern Min, and Cantonese, plus the Vietnamese and Japanese pronunciations of the characters in his questionnaire.