Uyu mugani bawuca iyo babona umuntu yangira ibyo agomba gukora maze akanashaka urwitwazo rukomeye rwo kubyihunza: ubwo nibwo bavuga ngo: “Arihadika ibitugunguru”.
Wakomotse ku mugabo witwa Nkurukumbi wanze gutabarira ingoma, ahagana mu mwaka wa 1300 (1264 -1295).
Uyu mugabo Nkurukumbi yabaye ho ku ngoma ya Ruganzu Bwimba. Bitewe n’uko Bwimba yimye ingoma ari muto, nyina Nyiraruganzu Nyakanga wo mu bwoko bw’Abasinga ni we wayoboraga igihugu afatanyije na musaza we wo kwa sewabo Nkurukumbi ya Nyebunga.
Mu bari bakomeye ibwami icyo gihe twavuga mo abiru nka: Nyaruhungura w’umutsobe, Cyenge wa Nyacyesa w’umukobwa (ukomoka kuri Mukobwa wa Nyacyesa), Gitandura wa Kingari umukurambere w’Abatandura hanyuma hakaza Mukubu wa Mushyoma w’umuha.
Muri icyo gihe u Rwanda rwari ruturanye n’ibihugu bibiri bikomeye aribyo Igisaka cyategekwaga na Kimenyi Musaya n’u Bugesera bwategekwaga na Nsoro Bihembe. Igisaka ariko cyo cyashakaga kwigarurira u Rwanda mu gihe u Bugesera bwo bwari bubanye neza n’u Rwanda.
Bari bararaguriye umwami w’Igisaka ko umwami uzigarurira u Rwanda ari uzaba yaravutse ku mwami w’u Rwanda. Ibyo byatumye Kimenyi yiyemeza kuza gusaba mushiki wa Bwimba witwa Robwa.
Umwami Nsoro Samukondo se wa Bwimba akaba yari yarasize umurage ko batazigera bashyingira umwami w’Igisaka bitewe n’uko yari azi iyo mitsindo yo mu Gisaka.
Ubwo rero Kimenyi Musaya yazaga gusaba Robwa; Bwimba yaramumwimye ariko nyina Nyakanga afatanyije na musaza we Nkurukumbi bamurusha imbaraga baramutanga bavuga ko gushyingira Kimenyi ari ukugwiza amaboko.
Mbere y’uko Robwa arongorwa kwa Kimenyi, Bwimba yashyize Robwa ku ruhande amubwira ko yagenda yagira atazigera abyarana na Kimenyi kuko babyaranye umuhungu ari we wazagaruza u Rwanda umuheto.
Robwa yarabyumvise arabyemera maze ajya gushyingirwa kwa Kimenyi yiyemeza kuziyahura igihe azaba atwite kugira ngo ahinduke umutabazi w’umucengeri. Ubwo rero Robwa yari amaze gusama inda; yahise abimenyesha musaza we. Hagati aho mu Rwanda bararaguje maze inzuzi zerekana ko Nkurukumbi ari we ugomba kuba umutabazi w’ umucengeri ugomba kugwa mu Gisaka kugira ngo urupfu rwa Robwa wari wiyemeje kwiyahura atwite ruzatere amakuba inshuro ijana Igisaka, bityo kizabe ari cyo gitsindwa n’u Rwanda.
Niko gusaba Nkurukumbi kuba umutabazi arabyanga, ndetse ashaka n’urwitwazo rw’uko arwaye indwara yo kuzana amagara bityo akaba atagomba gutabara arwaye iyo ndwara! Ubwo yihaditse mu kibuno amatugunguru (utwatsi dutukura) kugira ngo agaragare nk’uwazanye amagara koko. Ruganzu yaramubwiye ati: “Ubwo urwaye utyo byaba byiza ubaye ari wowe ugiye kugwa mu Gisaka ukazatuma icyo gihugu kizana amagara”! Nkurukumbi yakomeje kwanga ariko abifashijwemo n’umugabekazi Nyakanga mushiki we.
Nkurukumbi amaze kubatsembera atyo; abapfumu bongeye kuragura maze bemeza ko Ruganzu Bwimba ubwe aba umutabazi arabyemera.
Ariko mbere yo kugenda arabanza aca iteka ko ubwoko bw’Abasinga butazongera gutanga umugabekazi ku bw’igihano cy’uko Nkurukumbi yanze kujya kuba umutabazi.
Ruganzu Bwimba nta mwana yari yakabyaye wo kuzamusimbura ku ngoma, ariko icyo gihe umugore we yari atwite yenda kubyara. Ruganzu ahera ko agana ku nkiko (umupaka) y’i Burasirazuba ategereza ko bamubwira ko umugore we abyara mbere yo gutangira intambara.
Hashize igihe baza kumubwira ko Nyakiyaga yabyaye umwana w’umuhungu. Gitandura ni we waje kubimubwira ahita ahabwa ubutumwa bwo gusubira ibwami akajya kwita umwana izina rya “Rugwe”. Kuva icyo gihe abakomoka kuri Gitandura bahabwa kuzajya bita abana b’ibwami izina mbere y’uko umwami abiyitira.
Nyuma Ruganzu amaze kujya inama n’abo bari kumwe asigira igihugu Cyenge kugeza ubwo Rugwe azaba ageze ku myaka yo kuba yategeka. Amaze kurangiza ibyo atanga itegeko batangira intambara maze Ruganzu Abanyagisaka bamwicira ahitwa Nkungu hafi ya Munyaga icyo gihe hakaba hari hakiri mu Gisaka. Intumwa yahise ijya kubwira Robwa ko musaza we yatanze.
Ubwo Kimenyi yahise yereka Robwa ingomangabe Rukurura ibyo bikaba byari ikimenyetso cy’uko agiye kumugira umugabekazi w’Igisaka bityo akaba amuhojeje urupfu rwa musaza we.
Ako kanya Robwa yahise yiterura yijugunya ku ngomangabe Rukurura maze apfana n’umwana yari atwite. Ng’uko uko Robwa yabaye intwari y’umutabazi kimwe na musaza we Ruganzu Bwimba.
Naho Nkurukumbi nyirarume wa Ruganzu Bwimba wihaditse amatugunguru avuga ko yazanye amagara byo gutinyirira ingoma; ni we wabaye inkomoko y’umugani baca ku muntu ushaka inzitwazo zo guhunga ibintu bimugomba bakagira bati: “Arihadika amatugunguru”! Kwihadika amatugunguru: Guhimba urwitwazo rwo guhunga ibikugomba.
