I have had experience in meditation, I want to have experience of living and learning with Buddhist monks. Where in Asia can I experience this for 8 to 10 weeks to start?
Speaking from personal experience with stays at Zen monasteries in Japan:
It depends on what you mean by retreat. Many Zen monasteries in Japan offer "retreats" in their web pages, but this is not necessarily what is meant in Japanese Zen by a sesshin (接心). If you want to experience the daily life of Buddhist monks in Asia, I'd advise not joining a sesshin for your first time in Japan, as this is an extremely intense period for the monks, and if you do not fully master the local language and the temple customs you will struggle. First time around, I would advise you stay at one or more temples during a regular period.
If you want to sleep, meditate, eat, and work with the monks you can contact the head temple or administrative office of a Buddhist lineage in Japan and ask for possible periods and places to stay (also, indicate if you need some help with the language and customs, as this will be taken into account proposing possible stays to you).
Here are some links you may find useful:
Shoganji Monastery - Rinzai lineage
Soto Zen monasteries for foreigners in Japan - Soto Lineage
ShinShoJi Temple - Rinzai Lineage
Shunkoin Temple - Mindfullness
There's also shukubo in Japan, a kind of pilgrim lodging associated with nearby temples.
Many Westerners come to here to meditate, some become monks, some as laypeople.
International Buddhasāsana Meditation Centre
You might also be interested in this monastery which the abbot has traveled to the deep forests and mountains in Karen State and meditated for many years. It is also common that several monks go to the forest and return only when they achieve a certain level of enlightenment. https://goo.gl/maps/BgDTUBbbDvQ2
Note: Free of charge. Stay as long as you want. These are in Myanmar, so I am afraid you might end up like Jack Dorsey.
If you're searching for Theravada Buddhist retreat in Sri Lanka you can visit,
Well there are plenty of monasteries, so try to find videos by bikkhus online and then go to their website to find the contact info and ask them about retreats
ex in thailand: the famous http://www.forestdhammatalks.org/en/contact.php
the famous https://www.phrasuchart.com/contact/