This is what Nyerere, Karume agreed on Tanzania

Baba wa Taifa,Hayati Mwalimu Julius Kambarage Nyerere(kushoto) akibadilishana na Hayati Sheikh Abeid Amani Karume(kulia)

On April 26, 1964, The Father of Nation Mwalimu Julius Nyerere and the First Zanzibar's President Abeid Arnan Karume united Tanganyika and Zanzibar to form the United Republic of Tanzania. The Union was supported by what came to be known as the Articles of Union. Here is the original document of the articles as agreed by the founders of the two nations.

WHEREAS the Governments of the Republic of Tanganyika and of the Peoples' Republic of Zanzibar being mindful of the long association of the peoples of these lands and of their ties of kinship and amity, and being desirous of furthering that association and strengthening of these ties and of furthering the unity of African peoples have met and considered the union of the Republic of Tanganyika with the Peoples Republic of Zanzibar:

AND WHEREAS the Governments of the Republic of Tanganyika and of the Peoples' Republic of Zanzibar are desirous that the two Republics shall be united in one Sovereign Republic in accordance with the Articles hereinafter contained:-

It is therefore AGREED between the Governments of the Republic of Tanganyika and of the Peoples' Republic of Zanzibar as follows: -

(i) The Republic of Tanganyika and the Peoples' Republic of Zanzibar shall be united in one Sovereign Republic.

(ii) During the period from the commencement of the union until the Constituent Assembly provided for in Article (vii) shall have met and adopted a Constitution for the united Republic (hereinafter referred to as the interim period) the united Republic (i) ii) to (vi) shall be governed in accordance with the provisions of Articles

(iii) During the interim period the Constitution of the united Republic shall be the Constitution of Tanganyika so modified as to provide for;

(a) a separate legislature and executive in and for Zanzibar from time to time constituted in accordance with the existing law of Zanzibar and having exclusive authority within Zanzibar for matters other than those reserved to the Parliament and Executive of the united Republic;

(b) the offices of two Vice-Presidents one of whom (being, a person normally resident in Zanzibar) shall be the head of the aforesaid executive in and for Zanzibar and shall be the principal assistant of the President of the United Republic in the discharge of his executive functions in relation to Zanzibar;

(c) the representation of Zanzibar in the Parliament of the United Republic;
such other matters! as may be expedient or desirable to give effect to the united Republic and to these Articles.
(iv) There shall reserved to the Parliament and Executive of the united Republic the following matters-

(a) The Constitution and Government of the united Republic.
(b) External Affairs.
(c) Defense.
(d) Police.
(e) Emergency Powers.
(f) Citizenship.
(g) Immigration.
(h) External Trade and Borrowing.
(i) The Public Service of the united Republic,
(j) Income Tax, Corporation Tax, Customs and Excise.
(k) Harbours, Civil Aviation, Posts and Telegraphs.

<img src="https://www.juliusnyerere.org/uploads/nyerere-karume-b03.jpg" style="border: 0;" alt="image" width="380" height="260" />
<i>Mwalimu Julius Kambarage Nyerere akichanganya michanga ya ardhi ya Zanzibar na Tanganyika wakati wa Muungano 1964 huku (kulia) aliyekuwa Katibu Mkuu wa CCM Rashid Mfaume Kawawa akiangalia tukio hilo na nyuma (kushoto) aliyekuwa Rais wa Zanzibar Abeid Amani Karume akishuhudia tukio hilo.</i>

And the said Parliament and Executive shall have exclusive authority in such matters throughout and for the purposes of the united Republic and in addition exclusive authority in respect of all other matters in and for Tanganyika,

(v) The existing laws of Tanganyika and of Zanzibar shall remain in force in their respective territories subject-

(a) to any provision made hereafter by a competent legislature;
(b) to such provision as may be made by order of the President of the united Republic for the extension to Zanzibar of any law relating to any of the matters set out in Article (iv), and the revocation of any corresponding law of Zanzibar;
(c) to such amendments as may be expedient or desirable to give effect to the union and to these Articles.

(v) (a) The first President of the united Republic shall be Mwalimu Julius K. Nyerere and he shall carry on the Government of the united Republic in accordance with the provisions of these Articles and with the assistance of the Vice-Presidents aforesaid and of such other ministers and officers as he may appoint from Tanganyika and Zanzibar and their respective public services.
(b) The first Vice-President from Zanzibar to be appointed in accordance with the modifications provided for in Article (iii) shall be Sheikh Abeid Karume.
(vii) The President of the united Republic: in agreement with the Vice-President who is head of the Executive in Zanzibar shall;
(a) Appoint a Commission to make proposals for a Constitution for the united Republic.
(b) Summon a Constituent Assembly composed of Representatives from Tanganyika and from Zanzibar in such numbers as they may determine to meet within one year of the commencement of the union for the purpose of considering the proposals of the Commission aforesaid and to adopt a Constitution for the
united Republic.

(viii) These Articles shall be subject to the enactment of laws by the Parliament of Tanganyika and by the Revolutionary Council of the Peoples' Republic of Zanzibar in conjunction with the Cabinet of Ministers thereof, ratifying the same and providing for the Government of the united Republic and of Zanzibar in
accordance therewith.

EN WITNESS WHERE Julius K. Nyerere, the President of the Republic of Tanganyika, and Abeid Karume the President of the Peoples' Republic of Zanzibar have signed these Articles, in duplicate, at Zanzibar, on this twenty-second day of April, 1964.

Passed in the National Assembly on the twenty-fifth day of April, 1964.

Source: https://www.safarilands.org/