Firstly, the communist states of the Soviet Union and China...

Firstly, the communist states of the Soviet Union and China supplied vast amounts of weapons into Indochina in the 60's. This is a fact, even though they claimed otherwise, they were implicitly supporting North Vietnam's war against the US, which was verified by the Mitrokhin files, re: after the fall of the Soviet state. With the end of the war, these weapons would have become surplus to the needs of the people and become readily available to other insurgent groups in the area. I remember years ago, the going rate for a AK-47 in Sahel Africa was said to be USD$10 (don't know if it is true, but Mozambique has the AK-47 on their national flag)

Secondly, the Golden Triangle is one of 2 major heroin growing regions in the world. This place funded the Shan's civil war effort for at least the 80's and 90's. There is a lot of money in drugs. The Burmese state isn't that strong in the mountains

Third. I live near the biggest Karen community in Australia at Werribee (around 2~3,000 of them). They don't like Burmese, as many of them lived in refugee camps in Thailand for many, many years. The Karen and Shan resisted the Burma state's policy of Burmaisation and ethnic/ religious persecution and outright discrimination for 30 years.

So what do we have, recap

1. Lots of cheap weapons
2. Lots of potential money to fund the purchase of weapons
3. A deep mistrust of ethnic Burmese
4. A strong sense of who they are and what they prepared to do for self autonomy

Thus are they poor, YES, you are correct. Do they have guns in the mountains? If they don't, then the Burmese state will do to them what has happened to the Rohingya on the coast.

Side note : Sittwe, the capital of Rakhine state (that's where the Rohingya's live) is the location of an oil terminal that CHEC built for $10 billion, including an oil pipeline that runs through LASHIO to Yunnan. This is China's only way of importing oil into China if the Straits of Malacca get closed off due to a military confrontation with America (expect to see a PLA-N naval base there very soon), so this is a geo-strategic area for China and nothing that happens in the area would have happened without China's unofficial consent

Conclusion - If the jobs/ contracts at the mine site go to ethnic Burmese, then we only have to look to Grasberg and Bouganville to see what might happen. That is not ignorant, nor offensive