"...The raw material of U303 products is also exported to the USSR. Packed in wooden tea boxes. Loose tea of the third grade with tea number 5310 is about 25 kg per box. The receiving units in the Soviet Union were all tea packing and packaging plants (such as Moscow Tea Packing and Packaging Plant, Ryazan Tea Packing and Packaging Plant, etc.), which were packed and processed for sale..."
"...Comrade Wang Jixiang recalled that in the 1980s, trade between the Soviet Union and the East was mainly carried out in the form of barter, with tea being exported in exchange for engineering products. From 1986 to 1988, there were two types of first-generation taxis. The Polo in Kunming came from the Warsaw company FSO, and the Soviet Lada cars were purchased in exchange for Yunnan black tea exported by the company..."
Thus, it can be assumed that this box of tea was imported from China to the USSR (Poland) in 1986-1988.