Specifically thinking Korea and Japan (but not exclusively) pre-modern era. There's a lot of things that have its roots in China, but what about the other way around?
Area I'm most interested in - but not limited to - are imported technologies. What are some technologies, pieces of culture, and food the Chinese adopted that had significant impact?
A few things come to mind - Kung Fu, something we identify with Chinese had its roots in India. Corrected by /u/arkofarkoftheoaken
I also heard Swordmaking techniques that were from Tang China made their way to Japan, but then "lost" during the Mongol lead Yuan Dynasty - so after the Yuan, they began importing higher quality swords and sword making techniques back from Japan.
LIST OF INTERESTING THINGS WE'VE LEARNED SO FAR
So, I'm sticking incredibly close to my flair on this one. I know you said technology, and this doesn't really fit. But maybe you'll still find it interesting.
As you probably know there's a huge amount of linguistic borrowing into Korean and Japanese from Chinese languages. Some estimates say about 70% of Korean words in regular use as Chinese loans. Of course Japanese has a number a swell, and until recently both languages regularly used Chinese characters.
What isn't as widely known is that a number of modern Chinese words were actually borrowings from Japanese. The words for telephone and bank, for example, were words coined in Japanese but with corresponding characters, and then later borrowed into Chinese languages. This paper gets into some of the details if you're interested.
Just a minor correction, but Chinese martial arts or kungfu are documented in texts from the Spring and Autumn period (8th - 5th century BC) and the Warring States period (5th - 3rd century BC), prior to any substantial contact with India. The Gongyang Zhuan commentary (c. 3rd century BC) on the Spring and Autumn Annals mentions the practice of shoubo, an early form of unarmed combat. It describes how Zichang Wan reportedly killed Duke Min in 682 BC with a strike to the jaw. A boxing match in 632 BC between Chu Zi and Meng is documented in the Zuozhuan (c. 4th century BC). There's a legend that claims that Bodhidharma founded Shaolin martial arts in the 5th century AD, but Shaolin is neither the oldest nor the only school of martial arts in China. For more information on the history of Chinese martial arts, I would recommend Peter Lorge's Chinese Martial Arts: From Antiquity to the Twenty-First Century.
But returning to your original question, the answer that comes to mind is the folding fan. The folding fan is commonly associated with Chinese culture in popular media, yet its origins are Japanese. The Chinese fixed fan was brought to Japan between the 3rd and 6th centuries. By the twelfth century, two types of folding fan–the ''hiogi'' and the "bat fan"–had been invented in Japan. Japanese use of the folding fan is attested in Chinese and Japanese sources such as the Chinese Song Shi. Folding fans likely spread to China from Japan through Korea.
Alexander, Hélène. Fans. London: B.T. Batsford, 1984. Print.
Lorge, Peter Allan. Chinese Martial Arts: From Antiquity to the Twenty-first Century. New York: Cambridge University Press, 2012. Print.
I am surprised that nobody mentions Mahayana Buddhism and Xuanzang's epic journey to India to import Indian Buddhistic knowledge, is that too obivous? Whether there are lots of Japanese loanwords in Chinese is debatable, but definitely lots of Chinese words borrow their meanings from the Sanskrit.