China played a significant, if only a third party part in the cold war. During the beginnings of the era, China was on the side of the Soviet Union. Ideological differences brought an end to the loosely held alliance against the West. China became more economically tied to the US and Western Europe, even before the Iron Curtain fell, which could have been interpreted as a sort of neutrality, though there was still strife with Japan and India over border issues.
Through the cold war, China held a special relationship with Great Britain and Portugal regarding Hong Kong and Macau, respectively. Even as these two European and NATO aligned countries held territory well within striking distance of China, there was no significant military presence in either Hong Kong nor Macau in support of the western side of the cold war. In fact, after their respective handovers, the two territories became more militarized with the arrival of Chinese forces than they ever were as colonies.
A great deal of economic and social ties to mainland China kept otherwise aggressive elements at bay. Relations between the US and Europe at large warmed upon Deng Xiaoping's institution of economic reform.
The term of the military barrier that divided Communist China and the west was 'bamboo curtain'. Today there is hardly a 'bamboo curtain' drawn around China's borders at all. This term is applied to other not so forthcoming and confrontational countries in the region, such as North Korea.
China may have played a part in the fall of the Iron Curtain and the Soviet Union when the gradual separation between strategies in dealing with the west became less related to one another. The Soviet Union also depended heavily on fuel and food from China which dried up when western countries such as the US began offering higher prices for the products.
Where economic relationships failed with the Soviet Union and the west, they blossomed with China and the west.