Seventy years ago, Sikh, Rajput and Chinese regiments fought together against the Japanese in the battle of Hong Kong.
This is the kind of narrative you don't expect to hear in Beijing even if it pops up soon after dialogue between the rival militaries recently resumed after a tense year-long gap.
This week, a small audience of Indian diplomats and the Indian and foreign media, gathered to hear an illustrated talk of the defence attache's travels retracing the history of Indian troops in old war-torn China. It threw up nuggets of military history that may, if better known, ease some of the strain in building strategic ties.
"It's not well known that a day after Pearl Harbour, the Indian and Chinese regiments fought on the same side,'' said colonel G Jaishankar.
The armies staring down the disputed Himalayan boundary separating India and China may find it hard to imagine this shared slice of history from 1941. Two decades later, Indians and Chinese fought a war against each other.
In his travels as a history buff, the official photographed the transformation of landmarks from northern Beijing to southwest Yunnan. In northeast Dalian, the scene of a former British-Indian encampment is now an IT park.
"These are aspects of history we should be aware of,'' he said.
Stories have gone down in historic records, of Indian soldiers under Britain who fought opium wars and waded through drainage channels to help lift the siege of Peking's legation quarters in 1900. Photographs of Sikhs guarding the Shanghai concessions are sprinkled in landmarks including the Oriental Pearl Tower.
Some strands of the joint action of Indians and Chinese in December 1941 remain lost. About 585 Indians were commemorated as the commonwealth war dead in Hong Kong. Graves in 15 Chinese cemeteries were lost during the cultural revolution of 1966-76.
In the Temple of Heaven in Beijing, a curator showed Jaishankar a relic saved in storage. It is the only bell saved from a set of six bells used in Ming harvest ceremonies.
In 1994, the Indian army returned the bell, which was part of the British loot from Peking.
Jaishankar is still searching for an authentic Yunnan Rupee minted for trade between British India and the mountainous province.