Niandoubao, or sticky bean buns, have been one of the favorite foods for residents in Qinglong Manchu autonomous county, Hebei province, since they were introduced during the reign of Emperor Kangxi of the Qing Dynasty (1644-1911).

Locals use glutinous rice to make dough, then wrap red beans or other fillings inside. After being steamed, it becomes a delicious snack.

Relying on customs and local natural advantages, this simple folk food has spread from the local dining tables to countless households nationwide and overseas.

Located at the foot of North China's Yanshan Mountains, the county is a typical place for mountainous agriculture with abundant sunlight, large temperature differences between night and day and soil that's rich in minerals, making it a prime location for high-quality crops such as millet, sorghum and buckwheat, according to Jia Guozhong, head of the county's bureau of agriculture and rural affairs.

Historical records show that the millet produced in Qinglong was once presented in tribute to the imperial court during the Qing Dynasty and became known as "tribute millet".

"The various grains in Qinglong are of superior quality, benefiting from a combination of natural endowments and local people's hard work," Jia said, adding that the planting area for grain in the county has reached 8,000 hectares.

He said that the soil in these areas is neutral and sandy with a high organic matter content, which is beneficial for the growth of grain and the accumulation of nutrients.

Thanks to the natural advantages, Qinglong boasts a long history of growing grain, with a well-established agricultural development model.

Farmers in the county are skilled in the cultivation of grains, and also enjoy using it to make delicious food. Among them, two locals — Zhang Shengli and Zhang Quanli in the county's Longwangmiao town — spotted a business opportunity in 2013. They founded Shuanghesheng Ecological Agricultural Products, dedicated to the production of the traditional Manchu delicacy.

The company has produced a variety of foods, including the sticky bean buns, as well as chestnut buns, and date and chestnut steamed buns. Their success has come with the help of strong support from local policies. Currently, the company produces 72 product lines, with an annual production of over 5,000 metric tons, according to Zhang Minghui, the company's deputy general manager.

As more people choose to eat healthy food with no additives, the company's production has gradually expanded.

Its products are sold in many places across the country, including the Beijing-Tianjin-Hebei region, and provinces in Northeast and Southwest China, according to Zhang.

"We have established nearly 40 branches nationwide and exported our products to 19 countries and regions, including the United Kingdom, the United States, South Korea and Canada," Zhang said.

Qinglong has more than 30 manufacturers producing healthy grain foods. The county yields about 22,000 tons of grain annually, engaging over 80 professional cooperatives and family farms.

"I know that buns or noodles with local characteristics can help foster a major industry. With so many high-quality agricultural products of our own, we cannot always be content with the role of raw material suppliers," said Li Yaobin, the county's Party secretary.

Zhang Bao contributed to this story.