The ugly fact is that Baluch are not son of soil. The name Baluch itself derives from Balochistan , which was historically a Iranian Province. To this day they speak their dialect. The tribes are spread out all over Iranian Sistan Province , Iranian Balochistan and as far as UAE, Bahrain, Kuwait and Oman.
Present day Baluchistan is a conquered land which Pakistan got in 1947. It is only fair that it is conquered and colonised from people from other provinces. As ugly as this may sound.
Migration is a constant theme of Human history. Even history of present day Multan, upper punjab is rife with people, tribes and land cultivators who migrated from Indian states of Haryana, Rajhastan, and Indian Punjab. Most of the large cities of Punjab are actually cities established by British as Canan Colonies.