Starting at the turn of the 17th Century to the 18th Century, this geographic region was the scenery for many confrontations between Indians and colonists who increasingly entered their lands, pushing the cattle-raising frontier westward.
Although there are no references to an indigenous group named Atikum before the 1940s, there are many to one called Umã, which was aldeado (put in villages), along with the Xocó, Vouve and Pipipã groups, in 1802 by the friar Vital de Frescarolo, in the place where one of the present-day villages of the Indigenous Land is located. Such aldeamento did not last very long, and the Indians continued to roam through the interior of the Northeast Region, from Ceará to Sergipe, always avoiding cattle trails. In addition to the groups mentioned above, many Indians intermixed - and mixed with quilombola blacks (from communities of runaway slaves) - in such displacements.

Mentions to the Umã are the following: around 1696, they were seen in the São Francisco River valley; in 1713, they were on the banks of the Pajeú; in 1746, between the rivers Ipanema and São Francisco, in Alagoas; in 1759, in Sergipe; in 1801, they were aldeados in Olho d'Água da Gameleira (where the present-day village Olho d'Água do Padre, on the Umã Hills, is located), which they left in 1819; in 1838, they were found near Jardim, in Ceará; in 1844, they were again close to the former aldeamento, more specifically in Baixa Verde. While aldeado, the Umã group - called by many different forms at the time, such as Huanoi, Huamoi, Huamães, Huamué, Humons, Umã, Umães, Uman, Umãos, Urumã, Woyana - had to live alongside the Xocó and Vouvê. These three groups have always maintained themselves close to the Pipipãs. On the other hand, it is know that in 1852 there were still "índios bravios" (wild Indians) in the Umã Hills or in the vicinity. But in the mid-19th Century all information regarding these Indians ceased. The next information about them is from 1943, when the Atikum requested the SPI for the recognition of their lands.

On a study made on the occasion of the 50th anniversary of the city of Floresta, Alvaro Ferraz (1957) mentions the existence in the area of hills that had been settled by blacks since the slavery period: "Such phenomenon can be observed in the Umã and Crioulos Hills. In the Umã, they mixed freely with the indigenous group that lived there, which can be easily seen through the analysis of the human types of the Atikum-Umã village at the top of the hills". Such miscegenation caused this "tribe" to become known as "the blacks of the Umã Hills". Thus one may conclude that the population that ended up settling permanently in the Umã Hills was formed by groups (Indians, blacks and whites) with different traditions and cultures.