Menghai Tea Factory (勐海茶厂), trading as Dayi (大益), is the founding institution of modern ripened puerh production and the world’s most recognised puerh brand by volume and collector prestige. Established in 1940 in Menghai County, Xishuangbanna Dai Autonomous Prefecture, Yunnan Province — in the heart of Yunnan’s ancient tea-growing territory — the factory played the central role in the development of wo dui (wet-pile accelerated fermentation) technology in the early 1970s, creating the modern shou puerh style. The factory’s numbered recipe productions (identified by puerh factory codes) are among the most collected, traded, and forged teas in the world.
In-Depth Explanation
Historical development:
The factory traces its origins to the “Fohai Tea Factory” (buddhist name from the area), formally reorganised as Menghai Tea Factory in 1953 under PRC state management. Through China’s planned economy era, Menghai became the primary state enterprise producing and exporting Yunnan tea products, including both raw compressed puerh (sheng) and loose mao cha.
The wo dui contribution:
The factory’s most historically significant innovation came in the early 1970s. Working on demand from Hong Kong and Overseas Chinese markets for mellow, aged-tasting puerh (previously satisfied only by long-aged sheng), Menghai Tea Factory and Kunming Tea Factory together developed a controlled microbial fermentation process (wo dui, 渥堆) that artificially accelerated the aging of raw puerh in weeks rather than decades. By 1975, the factory had refined this into a reliable commercial process — giving birth to shou (cooked/ripened) puerh as a product category. This is arguably the most significant development in puerh’s modern history.
Numbered recipe cakes:
Menghai’s productions are most famously identified by four-digit codes (see Puerh Factory Codes). The first two digits indicate the year the recipe was created; the third digit the grade blended; the fourth (conventionally) identifies the factory. The most famous Menghai codes:
| Code | Description |
|---|---|
| 7542 | Created 1975; Grade 4 blend; factory code 2. Raw sheng beeng cha; the benchmark raw puerh production |
| 7572 | Created 1975; Grade 7 blend; factory code 2. Shou puerh; the flagship ripened production |
| 8582 | Created 1985; Grade 8 blend; factory code 2. Raw sheng; heavily aged versions are highly sought |
| 7262 | Created 1972; Grade 6 blend; factory code 2. Classic raw production |
These recipe numbers do not guarantee consistency — variations in harvest quality, leaf sourcing, and production conditions change results year to year. Dated cakes of the same recipe number trade at wildly different collector prices based on production year and storage history.
Privatisation and the Dayi brand:
The factory passed through financial difficulties in the 1990s and was restructured in 2004 into Yunnan Menghai Tea Industry Co., Ltd., a privately-held company using the “Dayi” (大益, “great benefit”) brand. Post-privatisation, Dayi aggressively expanded commercially while also producing prestigious collector productions. The Dayi brand became heavily traded — and speculated — on secondary markets in China, with some aged productions achieving prices rivalling fine wine investments.
Counterfeit problem:
The prominence of Menghai/Dayi productions makes them among the most counterfeited teas in the world. Wrapper reproductions, fake aged cakes, and relabelled productions are common at all price points. Authentication of serious purchases typically requires expert wrapper analysis, storage provenance, and tasting evaluation.
History
| Year | Event |
|---|---|
| 1940 | “Fohai Tea Factory” established in Menghai County |
| 1953 | Reorganised and renamed Menghai Tea Factory under state management |
| Early 1970s | Wo dui fermentation process developed (with Kunming Tea Factory) |
| 1975 | Shou puerh commercial production begins; 7542 and 7572 recipes formalised |
| 1990s | Financial difficulties; production quality fluctuates |
| 2004 | Privatised into Yunnan Menghai Tea Industry Co., Ltd.; Dayi brand launched |
| 2010s | Dayi becomes dominant force in China’s puerh collector and investment market |
Common Misconceptions
“Dayi and Menghai Tea Factory are different companies.” Dayi is the commercial brand of the same entity that was formerly called Menghai Tea Factory. The heritage and production facility are continuous.
“Older numbered cakes are always better.” Age adds complexity and value under good storage conditions, but poorly stored old cakes (humid or smoky) dramatically degrade. A well-stored 5-year-old cake in ideal conditions can surpass a poorly-stored 20-year-old.
“Only Menghai Tea Factory can produce 7542.” The four-digit recipe code system was originally an internal state enterprise designation. Post-privatisation, other factories have used similar-looking naming conventions. Only Dayi/Menghai produces the genuine 7542.
Related Terms
See Also
Research
- Jiang, H. & Zhang, X. (2015). Pu-erh tea and its microbial communities during pile fermentation: A review. Applied Microbiology and Biotechnology, 99(10), 4167–4181.
[Reviews the wo dui fermentation originally standardised at Menghai Tea Factory — the central innovation for which the factory is historically known.]
- Scott, J. (2011). Liquid Jade: The Story of Tea from East to West. Walker & Company.
[Contextualises Menghai Tea Factory within Yunnan’s tea history and the commercialisation of puerh during the 20th century.]
Last updated: 2026-04