Sri Lanka is not independent as one would think. There foreign policy gets the blessing from New Delhi. Bangladesh can purchase arms from China or Russia or Klingons but at the end of the day, their economy depends on Indian trade. Pakistan is another issue.China has already won the diplomatic war with India she has more allays in Indian ocean... With this pace China wont need for a material war to win India for a political gain.
Nepal and Bhutan are on the Indian payroll.
And China has more enemies than they have friends.
China is the most hated nation on the planet after the United States, and they bombed arabs to get that position.