Not totally true tho, those people lived their for generations and never got the same freedom/rights like other citizens
So with a Japanese user name you should know other countries namely JAPAN also do not give citizenship just because one was born there, and in fact large communities of Chinese and Koreans live there with significantly less rights than Japanese citizens.
and while poverty/economic issues started the leaders/politicans/military leaders blamed that group while they maybe responsible for a small issue but certainly not responsible for the big issue that is/was going on in the country. Years we saw headlines about buddhists killling muslims and it was basically this region that they were talking about (even if not all the attackers were buddhists and all victims were muslim but it is better for the headlines).
Your grammar and fundamental ideas here are hard to pin down, but I believe you're conflating the fact of Burma/Myanmar's decades long internal conflicts with other ethnic based militias (recognized as national minorities by Constitution) with the Arakan (SW Burma) issue which is fundamentally a national historic issue and not "poverty/economic" based. This is legacy of British colonialism which had subjugated Burma even integrating it to British Indian colonial regime, during which time large numbers of Bengalis moved to Arakan along with other Indians to Burma generally, this is indisputably recorded by colonial records. It IS historically established that some ethnic Bangladeshis had lived in Arakan before British and indeed before Burma had conquered it, these being invited by Arakan King who had ruled over areas of now-Bangladesh... But the British records undeniably show large #s of Bengalis moved there during colonial period, and "Rohingya" never accepted to distinguish these settlers. After regaining independence, large numbers of these Indians (including Pakistanis & Bangladeshis) who moved there during colonial occupation left to Indian territory, but "Rohingya" did not for whatever reason (rural location, illiteracy, integration with longer-existing Bengali community). This is national sovereign issue for Burmans because they don't believe they're obligated to extend citizenship to colonial settlers which they view Rohingya as.
Of note, during WWII Burmans in general fought to remove British from Burma, but Bengali in Arakan (i.e. Rohingya) chose to side with the British rather than sympathize with Burmese fighting for national liberation. When Burma later achieved it's independence, that triggered "Rohingya" "mujahideen" movement seeking to secede and join Pakistan which at that time also included Bangladesh. So it's pretty clear they consistently identified with Islam and Pakistan more than they ever did Burma. Despite the portrayal of "Rohingya" as ethnic designation, it realy fails any objective measure of that, after all, knowing majority of them moved there during British colonial era that would imply an ethnic difference to existing community yet no claims or evidence of that exist, and along with shared dialect it is clear they are objectively same ethnicity as Chittagong Bengalis. Refugees in fact will often not describe themselves as "Rohingya" rather as "muslims from Arakan". That Bangladesh has not whole-heartedly welcomed them IMHO has to do with radical Islam being prevalent amonst them, to the extent of cooperation with Afghan mujahideen, and the semi-secular Bengali government which fought Pakistan for independence not wanting to undermine it's political majority. That and being more very poor people to increase burden on already poor country, while also not being fluent in centralized national standard dialect as opposed to their own dialect which is actualy shared with SE Bangladesh / Chittagong region.
All of this is not to say that the "Rohingya" are not living in a legally precarious state, facing state organized as well as community based violence and hostility (this coming from Arakanese who should be noted are themselves minority within Burma at large, Arakan previously being it's own kingdom centuries ago). Much of this hostility, especially of the local community type, comes with fear based justifications largely revolving around threat of potential Rohingya local demographic dominance with higher birth rates due to cultural norms etc. I think approaching this issue from just one narrow angle is unrealistic and without prospect for lasting success. The legal implications of Rohingya/Bengali settlers during British era from Burman sovereigntist position cannot be swept away. At the same time, the idea a small component of "Rohingya" had long lived in Arakan previous to British may justify granting citizenship to some, even if all are not acceptable, especially given it is large population numbers which provoke Arakanese fears. Ultimately I believe other states need to accept their responsibility, namely Britain as well as Bangladesh and/or Pakistan. They should be able to accept and grant citizenship to majority of Rohingya, if Britain wants to pay Bangladesh to take a larger share so it doesn't itself, that is bilateral issue, and AFAIK other Muslim states have indicated tendency to support here e.g. Saudi Arabia, Turkey, and Malaysia. Bangladesh was founded on basis of being country for Muslim Bengalis, which Rohingya are, so trying to shut them out is nigh on incoherent, certainly Bangladesh is easiest new home for them to integrate given shared culture and language, but political and economic factors may not allow Bangladesh to take all of them even with economic support, so other countries involvement may likely be necessary, and that reasonably includes Britain who was liable for results of their colonialism during which population transfers occured. Financial support to Bangladesh (both direct and possible trade concessions, etc) is likely a critical part of solution IMHO.