Collecting arms, etc., with intention of waging war against the Government of India is defined under section 122 of IPC. Provisions under IPC section 122 explained here:

What is Section 122 of IPC:

Whoever collects men, arms or ammunition or otherwise prepares to wage war with the intention of either waging or being prepared to wage war against the Government of India, shall be punished with imprisonment for life or imprisonment of either description for a term not exceeding ten years, 1and shall also be liable to fine.

List OF IPC Sections