Looking for a route to travel from India to Myanmar, Laos, Vietnam and Cambodia and then back to India.?

Planning a one month trip from India to mainland South East Asia. My trip includes Myanmar, Thailand, Laos, Vietnam and Cambodia. Will it be possible to buy a return air ticket from anywhere in India to Bangkok with a stopover in any place in Myanmar? If not, please suggest some other route to actualize my trip. I am willing to travel overland as much as possible.