Esipanye, Porutugali n’abapapa bumvaga ko ibihugu byari bimaze kuvumburwa ari ibyabo. Mu mwaka wa 1455, Papa Nicolas wa V yahaye Abanyaporutugali uburenganzira busesuye bwo kugenzura ibihugu n’ibirwa by’Afurika biri ku nkombe z’inyanja ya Atlantika no kwigarurira ibyaho byose. Mu mwaka wa 1479, mu Masezerano ya Alcáçovas, umwami Alphonse wa V wa Porutugali n’umuhungu we, Igikomangoma Jean, bahaye Ferdinand na Isabella bo muri Esipanye Ibirwa bya Kanari. Esipanye na yo yemeye ko Abanyaporutugali biharira ubucuruzi bwo muri Afurika, bakanigarurira ibirwa bya Açores, Kapuveri na Madère. Imyaka ibiri nyuma yaho, Papa Sixte wa IV yemeje ayo masezerano, avuga ko ibindi bihugu byari kuzavumburwa mu majyepfo no mu burasirazuba bw’ibirwa bya Kanari, byari kuzaba ibya Porutugali.

Icyakora umwami Jean wa II wa Porutugali yavuze ko ibihugu byavumbuwe na Colomb byari ibya Porutugali. Abami ba Esipanye banze ayo masezerano, bajuririra papa mushya ari we Alexandre wa VI, basaba uburenganzira bwo gukoroniza ibihugu Colomb yari amaze kuvumbura no guhindura abaturage baho Abakristo.

Alexandre yatanze amategeko atatu asobanutse. Irya mbere ryitwaga ko “ryashyizweho n’Imana ishobora byose,” ryahaga Esipanye uburenganzira busesuye kandi buhoraho  bwo gutegeka ibihugu byari bimaze kuvumburwa. Irya kabiri ryashyiragaho umupaka uva mu majyaruguru ukagera mu majyepfo, wari ku birometero 560 mu burengerazuba bw’ibirwa bya Kapuveri. Alexandre yavuze ko ibihugu byo mu burengerazuba bw’uwo mupaka byavumbuwe n’ibyari kuvumburwa, byari ibya Esipanye. Nguko uko uwo mupapa yagabanyije isi mo ibice akoresheje ikaramu. Irya gatatu ryongereraga Esipanye ububasha ku Buhindi no ku bihugu byo mu Burasirazuba. Birumvikana ko ibyo byarakaje Umwami Jean, kuko hari hashize igihe gito abayoboke be bigaruriye amajyepfo y’Afurika, bikongerera Porutugali ububasha yari ifite ku nyanja y’u Buhindi.

Jean amaze kurambirwa Alexandre, * yagiye kwivuganira na Ferdinand na Isabella. Umwanditsi witwa William Bernstein yagize ati “kubera ko abami ba Esipanye batinyaga Abanyaporutugali bitewe n’uko bari abagome kandi bakaba bari bahugiye mu kwigarurira Amerika, bagiranye imishyikirano kugira ngo bagire ibyo bumvikanaho.” Ni yo mpamvu mu wa 1494 basinye amasezerano yitiriwe umugi yabereyemo wa Tordesillas.

Amasezerano ya Tordesillas yagumishijeho urugabano Alexandre yari yarashyizeho ruva mu majyaruguru rukagera mu majyepfo, ariko arwimurira ku birometero 1.480 ugana mu burengerazuba. Mbese ni nk’aho Afurika yose na Aziya byari ibya Porutugali, naho Amerika ikaba iya Esipanye. Icyakora kwimura urwo rugabano byatumye ibindi bihugu byari kuvumburwa, urugero nka Burezili, bijya mu maboko ya Porutugali.

Kuba haratanzwe amategeko yemerera Esipanye na Porutugali gukoroniza ibihugu bishya bari bahawe no kubirwanirira, byatumye hameneka amaraso menshi. Iyo myanzuro yirengagije uburenganzira bw’abaturage b’ibyo bihugu kandi ikurura amakimbirane yamaze ibinyejana byinshi hagati y’ibihugu byategekaga n’ibyo ku nkombe byashakaga ubwigenge. Ibyo byatumye abo baturage bakandamizwa kandi banyunyuzwa imitsi.