Story highlights Indian PM Modi arrives in China this week

Relations between China and India haven't always been harmonious

But growing trade provides common ground

Haiyan Wang is the managing partner of the Washington DC-based China India Institute. Anil K. Gupta is the Michael Dingman Chair in Strategy & Globalization at the Smith School of Business, The University of Maryland. They are the coauthors of The Silk Road Rediscovered and Getting China and India Right. The opinions expressed here are solely those of the authors.

(CNN) When President Xi Jinping welcomes Indian Prime Minister Narendra Modi to China on Thursday, both leaders will be well aware that, by 2025, their nations will be two of the three largest economies in the world.

Geopolitical tensions notwithstanding, economic imperatives demand that collaboration between the two giants help mitigate historical mistrust and future rivalry.

As immediate neighbors and old civilizations, China and India have long enjoyed mutual harmony spanning almost two millennia.

Yet, the half century since India's independence in 1947 and Chairman Mao Zedong's establishment of the People's Republic in 1949 has been anything but harmonious.

Deep freeze

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