A lokacin yakin duniya na biyu bayan yakin duniya na biyu, burin samun kasa mai dunkulewa da hadin kai ya haifar da kudurin kafa kasar Malaysia.Tunku Abdul Rahman, Firayim Minista na Malaya, ya ba da shawarar farko da shugaban Singapore Lee Kuan Yew, da nufin haɗa Malaya, Singapore , Arewacin Borneo, Sarawak, da Brunei.^[83] Tunanin wannan tarayya ya sami goyon bayan ra'ayin cewa za ta rage ayyukan gurguzu a Singapore da kuma kiyaye daidaiton kabilanci, tare da hana Singapore-mafi rinjayen Sinawa mamayewa.^[84] Duk da haka, shawarar ta fuskanci juriya: Ƙungiyar Socialist Front ta Singapore ta yi adawa da shi, kamar yadda wakilan al'umma daga Arewacin Borneo da ƙungiyoyin siyasa a Brunei suka yi.Don tantance yuwuwar wannan haɗin gwiwa, an kafa Hukumar Cobbold don fahimtar ra'ayin mazaunan Sarawak da Arewacin Borneo.Yayin da binciken da hukumar ta yi ya nuna goyon baya ga hadewar Arewacin Borneo da Sarawak, 'yan kasar Brunei sun ki amincewa da hakan, wanda ya kai ga fitar da Brunei daga karshe.Dukansu Arewacin Borneo da Sarawak sun ba da shawarar haɗa su, wanda ya haifar da yarjejeniya mai maki 20 da maki 18 bi da bi.Duk da waɗannan yarjejeniyoyin, damuwa ta ci gaba da cewa ana lalata haƙƙin Sarawak da Arewacin Borneo na tsawon lokaci.An tabbatar da shigar Singapore tare da kashi 70% na al'ummarta suna goyon bayan hadewar ta hanyar kuri'ar raba gardama, amma tare da yanayin yancin cin gashin kai na jihohi.^[85]Duk da waɗannan shawarwari na cikin gida, ƙalubalen waje sun ci gaba.Indonesiya da Philippines sun ki amincewa da kafa Malaysia, inda Indonesiya ta dauka a matsayin "necolonialism" da Philippines na da'awar Arewacin Borneo.Wadannan adawar, hade da 'yan adawa na cikin gida, sun jinkirta kafa kasar Malaysia a hukumance.^[86] Bayan sake dubawa ta ƙungiyar Majalisar Dinkin Duniya, Malaysia an kafa shi bisa ƙa'ida akan 16 Satumba 1963, wanda ya ƙunshi Malaya, Arewacin Borneo, Sarawak, da Singapore, wanda ke nuna wani muhimmin babi a tarihin kudu maso gabashin Asiya.