Most guides, explanations and tips for this achievement rely on expansion mechanics to some extent. Me, being the poor brazilian that I am, wanted to get this achievement despite lacking the expansions. To do that, I had to be a little creative...

Portugal´s situation and positioning in Europe is key to get this achievement. In this image, you can see:

1. Castile to the East. Your main ally, but who can drag you into some pretty nasty wars if you don´t pay attention.
   
2. Morroco to the South. Along with the other nations of Maghreb, they are the main enemies of the Iberian Kingdoms.

Since Europe is not a priority in this achievement, you should work towards maintening the peace in the area, for Portugal at least, so as to not disrupt the campaings you are going to undertake in Africa.

The First Step you should take is to break the alliance with England. The Hundred Years War is not a conflict you want to be part of.

After that, you must analyse the situation in Iberia. Setting rivals too early might get Tunis and Morroco, for example, to ally each other. Its is not a necessity but ideally, the 3 big nations of Maghreb, Morroco, Tlemcen and Tunis, must not be friends with each other. Morroco specially needs to be isolated, so as to not declare war on you for Ceuta.

If Morroco does have a big ally, be sure to ally Castille in case of a war. Being alone as Portugal is not a good idea, since the AI can decide to attack you.

To help Castille in their war against Granada is not a big deal. Make sure to not spend too much money or manpower. Use only your navy to help. If Castille ever calls you into a bad war or in a bad time, don´t be afraid to break the alliance. They almost never turn hostile to Portugal, and will accept another ally offer in the future.

As such, you must try to conserve the few resources the kingdom has so as to have money for emegencies. DELETE ALL YOUR FORTS, you won´t be using them! Don´t forget that there is one in the capital! Lower the army expenses whenever not using them, and if at war and not using the navy, lower that maintenance too.

Portugal is not only poor in money. The Manpower of Portugal can go down pretty fast if you do not pay attention to what you´re doing. Rely on mercenaries if need be. Remenber that, regular cavalry is cheaper than mercenary cavalry. If you are going to use mercs, employ them in the infantry.

Another resource that will become scarce during the playthrough is admin, diplo and military points. Use them wisely, especially in the early game! A lack of admin and diplo points can slow you down and ruin your run.

There is an admin point 2 advisor that you can get at the beggining of the game. Don´t miss him out. For advisors, you should try to have a 2 in admin, 1 in diplo, and a discipline or morale guy in case of emergency.

Time is also short. The way around Kongo is long, but the Cape of Good Hope is way longer! You don´t have expansion mechanics to help you in your colonization, so the way through Africa is the only way to go! Be sure to meet your goals, otherwise you will be stuck in the East Coast of Africa in 1499.

The Pope is your friend! Be sure to use the Papacy mechanics to your advantage. Improve relations with the Pope, and even ally him. He usually wont go to war, but if he calls you, you can always refuse. The bonus you are going to use the most is the 15% national income modifier.

The Renaissance is a threat. It will make tech up harder. The only way to surpass this issue is embracing, but it does take its time to spread in Portugal. After the Renaissance spawned though, you can develop Lisboa and Porto, you bigger cities, which adds up to the Renaissance spread. Having a +20 development city also helps the spreading. Don´t waste too much in it though. It usually is good to do this only when the tech cost is 20% or higher.

As of 1444, Portugal is stuck with a regency. This is the time to make money, hire advisors, explore the world and do diplomacy.

1. Delete all your forts.
2. Lower army maintenance.
3. Hire the admin 2 advisor.
4. Hire a diplo 1 advisor.
5. Build 2 cogs, to complete the naval mission.
6. Ally Castille.
7. Befriend the Pope.
8. Explore a lot.

In regards to States management, theres a trick you can do. After getting some mil points from the nobles, develop Ceuta until it reaches 10 development. After that, you can grant Ceuta to the Burghers. You won´t get as many diplo points without doing this, since the Burghes have low influence in Portugal.

In regard to points, don´t take any diplo tech. Save these diplo points for latter, when you get the colonization idea. You need 1200 diplo points do get the first 3 bonuses of the colonization idea, and also unlock the "Henry the Navigator" national bonus. These Bonuses will extend your colonial range, which will play a important part latter.

You are allowed to tech up admin and mil. For admin, unlock one idea group as soon as you can, to spend the diplo points storage.

The objective is to wait for the regency to end. The end of it gives a event wich increases stability.
You´re are going to need it, because we can´t wait to colonize the islands. Colonization takes too much time. You will need to no-cb Jolof so as to jump over one of the colonization fences, as such taking a stability hit.

The war with Jolof should not be a problem. It´s a weak country, and usually doens´t ally strong neighbors. You need to get the 3 coastal provinces Jolof has to suceed. Attack as soon as the regency ends and the event fires, because time is precious. Get only the coastal provinces, don´t be greedy. Vassalizing and taking provinces will hit your admin/diplo points storage. Remenber to core them as soon as possible.

After the conquest, go for the colonization ideas, take 3 bonuses and you will be able to colonize a island near Kongo, which is the next target.

Kongo is where the difficulty starts to rise. The nation of Kongo is not as weak as Jolof, and if that kingdom allied a lot of its neighbours, it might prove to be a hard target. Theres no way out though, you need to kill Kongo.

The mission here is to get to the other side of the region, to border that uncolonized province that conects the Kongo region with the next target, Kilwa. To do that, don´t go around annexing everything, conquer your provinces in a line, always choosing the cheaper ones and the nearest to the target.

In wars, getting a discipline or morale advisor is reccomended. Always try to preserve manpower, and don´t get locked in truces! Kill all the rebels and raise the autonomy of the provinces.

Coring here will not be a problem. You can core a lot of provinces at the same time, but the range limit will start to show up. Conquer and core near the uncolonized province and colonize it as soon as you can.

A conquistador is highly needed for this part. You will need to discover a lot of provinces, and it does take time to do so. Movement of troops also is pretty slow in this region, consider this when calculating how much time is left.

In the beggining of this part, you already got what you needed from the colonization ideas. Don´t spend more diplo in that. You need now to tech up on diplo, because by tech 7 or 8, you get another buff to colonial range. All these colonial range buffs will be needed for the final part, where you need to reach an island in the East Indies for the achievement.

On rebels, you can reduce them by raising estability and hiring the -2 national unrest admin advisor. Also, try to store some admin points. You might need it in an emergency.

I don´t know if it is coded or something, but between 1460-1480, a lot of times during my runs I ended up on a regency. YOU SHOULD BE CAREFUL WITH YOUR KING! Also, sometimes I was in risk of being inherited by the king of Castille. Pay attention about those things, or it may ruin your perfect game.

The main problem that this grand strategy of mine resolves is cutting the time it takes to surpass the Cape of Good Hope, and it reduces the time Kilwa has to grow and expand. However, Kilwa is still a strong enemy. Most of the time, it will catch up to you in military tech, which is bad because that is one of the best advantages a european nation can have.

Thats why you need to be prepared here. Hire a good miltary advisor, have more troops, and stay at least in the same military tech as them. Before trying this Kongo-Kilwa strat, trying to go around the Cape of Good Hope, I struggled many times in my war against them. For some reason, bad events would happen and reduce my stability or Kilwa would just roll a lot of nines in battle and obliterate me. On my first run I had so many loans, that after I won the war I got bankrupt, which destroyed the entire campaign.

Also, the logistics is important. If you have a rebellion in the Kongo region, it will take a lot of time to go back and kill it. Its usually best to finish the war first then go for the rebels. And, to have no rebels at all, increase autonomy, get stability 3 and a national unrest advisor. Admin points aren´t that important anymore, except for coring provinces. Use it to your liking.

By the time you colonize the province connecting Kongo to Kilwa, you will be able to spread war in Kilwan territory. However, there is a problem. To core anything beyond the colony, you will need to finish colonizing first. Also, you won´t be able to core it all at once. You will need to core it one at a time until you reach the coastal provinces. Because of coring range, you will only be able to core adjacent provinces.

Thats why time is key here. The coring process takes 2 to 3 years to finish. You need to conquer everything you need in this area before 1480, otherwise you might not be able to core the provinces you need to extend the colonial range to India and the East Indies.

Kilwa, for some reason, likes to go for Madagascar first, before eating some parts of Mutapa and the other nations around. I didn´t need to go for their Madagascarian provinces in my run though.You only need 5 provinces from them, the ones who complete one of the missions and liberates the India event.

Remenber that, along with the 5 provinces, you will need to colonize the small island in the Mozambique area to complete the mission.

If you managed to outbest Kilwa by 1480, you are probably settled for a win. You just need to get Goa by event, and have coring range for Diego Garcia.

To get Goa, just complete the Portuguese missions until you complete the "Push to India" one. Its literally a free province.

Diego Garcia, on the other hand, might be a problem if you don´t have colonization range. Thats why I said that, after taking the 3 colonization idea bonus, you need to focus on the tech up. The diplo tech that increases colonization range will make you be able to colonize Diego Garcia.

Also, a little note. You don´t need to core the provinces or finish colonizing them for this achievement. Owing it only already counts. But, to get to Diego Garcia, you need to core your way in Africa. Colonization range is tied to the nearest core port.

For the colonist to reach Diego Garcia will take some time too. Take that into consideration.

Thats it! You have done it! Henry the Navigator would be proud of you! Huehuehuehue.

If you have any questions, or some sugestions or corrections, be sure to comment.