I see many people in this thread are promoting the idea of China-India strategic alliance. I have stated before like many others here, that it is wishful thinking, not going to happen. Here is why:
World-systems theory - Wikipedia, the free encyclopedia
Lets look at current core nations in blue. China is going to be a core nation in 15-20 years, when it reaches parity with the US in most fields of science, technology and weapons systems. During this time it does not want any diversionary conflict or pressure to hamper its continued rise.
So for China, this interim period is well suited for economic engagement with India, to make money and to lure India away from closer alliance with the West.
But once China reaches parity with the US, then it will no longer have any need to keep India away from a pro-West alliance. From that point on, China may change from a friendly neighbor to a more neutral and indifferent neighbor of India.
Now lets fast forward and look at the situation in 2050.
List of countries by past and future GDP (nominal) - Wikipedia, the free encyclopedia
List of countries by past and future population - Wikipedia, the free encyclopedia
China: population 1.3 billion, total nominal GDP 71 trillion
India: population 1.6 billion, total nominal GDP 38 trillion
USA: population 420 million, total nominal GDP 38 trillion
This means that by 2050, India has the potential to beat the US in size of economy and it will set its sight on China as its main rival and competitor.
Nothing can change the fact that India will be a nation that is going to be around 25% bigger than China in size of population. And for the foreseeable future, from 2030 or later, it will be the main rival and competitor for China on the global stage for raw material resources and market share for finished industrial products. The West will remain on the scene as the 3rd pole, and inevitably it will grow closer to the underdog India, in the future China vs. India competition.
In the security sphere, each will become core nations and seek out nations that will be willing to join its sphere of influence as semi-periphery or as periphery nations, just like the US is and will remain leader of the West+important non-Nato allies.
So billion plus nations like India or China are natural rivals and competitors, not natural allies and it is wishful thinking to think that they can become strategic allies, just because they are willing to engage in mutual business to make money.