Aden:
At the beginning of 1419, Aden was a small, single province country with much potential, thanks to the moderate wealthy (compared to others in the era) Cneter of Trade found in the capital city. Unfortunately for the young Sultanate, the military was non-existent, and the navy consisted of a measly 5 ships. Hadramut, Aden's eastern neighbor, was an ally and vassal, but relations only started at around +60.
Aden's sliders:
The first sultan, An-Nasir, was a decent leader, somewhat capable at diplomatic and administrative tasks, but inept at the art of war. As his reign began, he demanded that the local bedouin leaders surrender their ability to raise taxes to the central government - the first move towards a centralized government in Aden. Alongside this, Sultan An-Nasir announced that the top priorities for research would be land and trade, in order to bolster the military's ability to wage war in the harsh terrain of the Arabian Peninsula and to ensure that merchants can capitalize on the opportunity presented by the Center of Trade found in their own back (or front) yard.
In order to remedy Aden's lack of military prowess, the Sultan called for the creation of a standing army. 4,000 infantry and 1,000 cavalry troops were recruited.
On 4 September 1419, at the urging of his favorite advisor and Imam, Sultan An-Nasir declared war on the heretical (Shiite) state of Yemen, directly to the north of Aden. Another 3,000 infantry troops were recruited and combined with the main army. After sufficient training, the army was sent northwards to besiege the Yemeni capital. After a three day battle the Yemeni army disintegrated, and the brave soldiers of the Sultanate of Aden were free to besiege Yemen.
During the course of the siege, the son of the Sultan came of age. As a gift, his father gave him a present the young heir could only dream of: the beautiful niece of the Sultan of Mahra.
On 9 January, 1421, after well over a year of starving out the city, the Army of Aden liberated Yemen. Despite the religious differences, the Yemeni populace was surprisingly docile and didn't pose a major threat to internal stability and order.
The Yemenis are Welcomed to the Sultanate:
That spring, the military was downsized in order to help ease the budget deficit. To counteract this, the Sultan's son convinced his father-in-law, the Sultan of Mahra, to join the alliance of Aden and Hadramut. Aden quickly gained military access to all three of the members of the alliance, just in case it needed it some day.
Sometime in 1423, a trio of brave coffee merchants set off to the distant city of Samarkand. People there must really like coffee (Aden's finest cash crop!), as they have tremendous success. Two more follow the next year, bringing the total up to five.
Sultan An-Nasir decided to investigate what lay beyond the vast deserts of Arabia. He traded maps with the Mamluks, and learned of a continent called Europe, which was evidently the center of the world!
On 6 January 1424, Sultan An-Nasir was assassinated by disgruntled Bedouins while training his falcon. His son, the newly ascended Sultan An-Mansur, began hording money in the state treasury, saving it for the promotion of Bailiffs.
Sultan An-Mansur Ascends:
In fall of 1426, an elidgible bachelor from Morocco appears before the court. The Sultan was hardly in a position to turn him away empty-handed after such a long journey, and allowed him to marry his niece.
After four largely uneventful years, Sultan An-Mansur grows tired of his stressful job, and abdicated in favor of the competent, yet not brilliant, governor of Yemen, who becomes Sultan Zahir.
Sultan Zahir Ascends:
Sultan Zahir, knowing the importance of good administration, orders the promotion of a bailiff in Aden in March of 1428 in order to maximize tax revenue. The move, while somewhat unpopular, was built on sound economic theory. He announced that he was saving money to promote a bailiff in Yemen, too, and that his top priority was fixing the struggling economy.
As 1 January 1430 came around, Aden found itself in a position to grow over the next few decades. It had expanded through the annexation of Yemen, established itself as the dominant trading power in Arabia, and started to build up its infrastructure. It was poised to make a move.
I'm playing a game as them atm and it find them to be quite entertaining 
