As for the land of Saba' it was said that the city was located between two mountains. This city was very prosperous. Allah had blessed them with gardens of sweet tasting fruit, every tree in that garden was always producing fruit. However, Saba' would be flooded during rainy days when water seeped down the two mountains on either side of the village. To combat this, a large and advanced dam was constructed out of wood and stone. It had multiple levels for people to collect water and a huge canal system below which helped to irrigate the plantations. The weather was good, and no vermin were present on the land. Indeed, Allah had given them many blessings.
However, as years passed on, the people started forgetting about Allah. They forgot that Allah was their Creator, the One who blessed them with a prosperous and beautiful land. They started worshipping the Sun, asking it for blessings and supplication. Their leader at the time was a woman, Queen Bilqis of Saba' who was the daughter of one of the Tubba' kings.
The Tubba' kings were mostly pagans. They worshipped idols. They were also very aggressive kings, and they forcibly conquered the land until they reached the land of Samarkand (now in Uzbekistan). It is said that Samarkand recieved its name because of a Tubba' named Shammar Yahr'ish al-Manawu, who destroyed a pre-existing city there, hence the name ‘Shammar-Kand’ which means “destroyed by Shammar.” The Tubba' were one of the leading superpowers of the world alongside the Romans (Byzantines) and the Sassanians of Persia.
Queen Bilqis, upon meeting Prophet Sulayman, peace be upon Him, embraced Islam, and her kingdom did too. But when she died, the Sabaeans went astray, and they reverted to polytheism. Allah sent His messengers to teach the Sabaeans the right ways and guide them back to Islam. The people of Saba' were defiant and they did not listen to the messengers. So, Allah unleashed his wrath on these people. Rats were sent into the dam and weakened the structure, causing water to leak out. The Sabaeans noticed this one day, and they put cats in the dam to eat the rats, but Allah's decree had come, and the rats overpowered the cats. The rats gnawed through the support structures of the dam, until it was so weak. The structure of the dam soon collapsed and water, yes, all the water stored for more than hundred years, spilled out with great force. The massive flood destroyed the city of Saba' and their gardens, and many people were drowned. After the flood, Allah turned the trees in the gardens into trees with bitter and foul tasting fruits. The survivors of the great flood packed up their belongings and moved to various locations, where they became the progenitors of several Arab tribes.
Those who followed the Tubba' kings moved to Himyar. They elected a new Tubba' amongst them, and the paganism continued. They even distributed idols to the people of Makkah, where the tribes there worshipped. During that time, it was the period of Jahilliyah after Amr ibn Luhay al-Khuza'i had introduced idol worship into Makkah. However, one day, one of these Tubba' kings invaded the city of Madinah, as his son, the governor of that city, had been assaulted by a local man. The Tubba' was very angry and he raided Madinah, laying siege to it and cutting down the palm trees which were used by the locals to gain income. This siege went on for many days, but the residents of Madinah adopted a strange attitude- they would resist against the Tubba' at day and provide him food at night. This made the Tubba' feel ashamed, and later, two scholars of the Jews confronted him and told him that he would never conquer Madinah at all, as it was the final migration place for an upcoming Prophet of Allah. The Tubba' was thus persuaded to leave Madinah. He developed an interest in the religion of Prophet Musa, peace be upon Him, the correct religion before the coming of Jesus. At that time, the Arab Jews followed the religion of Prophet Musa. So, the Tubba' brought the two Jews with him, and he passed by Makkah. He wanted to destroy the Holy Ka'bah, which was filled with idols, but the Jews informed him about the greatness of the Ka'bah, and they encouraged him to do Tawaf around the Ka'bah. The Jews also told him that a rival tribe, the Banu Huzayl, had prevented the Jews from venerating the Ka'bah. So the Tubba' ordered the Banu Huzayl to repent but they refused, so he cut off their hands and feet. The Tubba' then performed his Tawaf around the Ka'bah, and then he sacrificed some sheep and distributed the meat to the residents of Madinah. He also set some new guidelines to the Ka'bah, that is, no blood sacrifices or idol worship should be performed there. Then, he returned to Himyar to invite his people to Islam. His people accepted Islam after they forced him to testify in front of a large fire pit. After that, the Jewish scholars helped to convert the population to monotheism. But the Tubba' eventually died after he was attacked in a revolt by his own soldiers, then his son succeeded him. Ibn Kathir records in his book Al-Bidayah wan Nihayah that the name of this Tubba' was Abu Karib As'ad al-Himyari, and him and his son Hassan Yuha'min were the first Himyarites to convert to the religion of Prophet Musa. Then this next Tubba' died too, after he was killed by his brother, due to influence by the tribes of Aqyals. So the Sabaeans went astray and reverted to polytheism. Allah says in Surah Qaf 50:12-15 that He sent down His divine wrath on the people of Himyar (called people of Tubba' in the Qur'an) after they had rejected some messengers who intended on advising them.
It was narrated that Tamim ibn Abdur-Rahman said that Ata' ibn Abi Rabah said, “Do not revile Tubba' as the Messenger of Allah ﷺ has forbidden reviling him.” And, of course, Allah knows best, all praise is due to Allah.
Sources
Holy Qur'an - Surah Saba' and Surah an-Naml
Ibn Kathir - Tafsir Ibn Kathir on Surah Ad-Dukhan and Surah Saba', and the book Al-Bidayah wan Nihayah volume 3, page 122
Ibn Ishaq - As-Seerah an-Nabawiyyah
Tim Mackintosh-Smith - Arabs: A 3000 Years History of Peoples, Tribes and Empires (note: This was only used for the legend on Samarkand's origin as stated in paragraph 3)