My English is very bad, but it seems to me that you're confusing the dates when the pots were imported and when they were made.
Bjorn Bjorholm talks about this subject here
www.bjornbjorholm.com
How so?
Bjorn has confused the history a bit or muddled what it means. He says that the Japanese made Nakawatari and Kowatari pots
popular in the 70's and 80's. In other words, what was already there (or searching out similar things in China), became fashionable. That doesn't mean Nakawatari or Kowatari pots weren't already in Japan. They were, They just weren't part of a popular trend. The actual export from China to Japan happened a lot earlier than the 1970's. It was part of a greater export exchange between China and Japan dating back centuries. The Japanese valued the "refined" esthetics of Chinese stuff for a very long time. Bonsai is one of the exports from China to Japan, for instance. The "Iiterati" style is a direct result of that exchange as well. The two "crossings" were part of freer trade between China and Tokugawa and Meiji eras in Japan, part of a widening of large-scale trade in the 1860's.
It's a long complicated history.
"Containers exported to Japan during the 17th and 18th centuries would be referred to as
Kowatari ("old crossing"). Extremely elegant and later harmonizing well with old dwarfed trees, these were made between 1465 and about 1800. Many came from Yixing in Jiangsu province -- unglazed and usually purplish-brown -- and some others came from around Canton, particularly during the Ming dynasty (1368-1644). Some porcelain containers were starting to be used for plants at this time in China.
By the year 1700, containers now had a finer texture than those made during Ming times, and these featured a tremendous variety of patterns. The practice of carving calligraphy or paintings onto container surfaces dates from this time.
Pots
exported from China to Japan between 1816 and 1911 (especially in the late 1800s) were called
Nakawatari ("middle-crossing") or
Chuwatari. Unglazed shallow, rectangular or oval-shaped stoneware pots with carved feet and very large drainage holes were used at ancestral shrines and treasured by the Chinese. These antique containers were originally incense burners for outdoor use in cemeteries. "