Shamsu'd-Din was succeeded by his son Ruknu'd-Din. The latter adopted the title of malik, which all succeeding Kartid rulers were to use. By the time of his death in Khaysar on September 3, 1305, effective power had long been in the hands of his son Fakhru'd-Din. Fakhru'd-Din was a patron of literature, but also extremely religious. He had previously been cast in prison by his father for seven years, until the Ilkhanid general Nauruz intervened on his behalf. When Nauruz's revolt faltered around 1296, Fakhru'd-Din offered him asylum, but when an Ilkhanid force approached Herat, he betrayed the general and turned him over to the forces of Ghazan. Three years later, Fakhru'd-Din fought against Ghazan's successor Oljeitu, who shortly after his ascension in 1306 sent a force of 10,000 to take Herat. The malik, however, tricked the invaders by letting them occupy the city, and then destroying them, killing their commander Danishmand Bahadur in the process. He died on February 26, 1307. But Herat and Gilan were conquered by Oljeitu.

Fakhru'd-Din's brother Ghiyathu'd-Din succeeded him upon his death; almost immediately, he began to quarrel with another brother, 'Ala'u'd-Din. Taking his case before Oljeitu, who gave him a grand reception, he returned to Khurasan in 1307/8. Continuing troubles with his brother led him to visit the Ilkhan again in 1314/5. Upon returning to Herat, he found his territories being invaded by the Chagatai prince Yasa'ur, as well as hostility from Qutbu'd-Din of Isfizar and the populace of Sistan. A siege of Herat was set by Yasa'ur. The prince, however, was stopped by the armies of the Ilkhanate, and in August 1320 Ghiyathu'd-Din made a pilgrimage to Mecca, leaving his son Shamsu'd-Din Muhammad in control during his absence. In 1327 the amir Coban fled to Herat following his betrayal by the Ilkhan Abu Sa'id, where he requested asylum from Ghiyathu'd-Din, whom he was friends with. Ghiyathu'd-Din initially granted the request, but when Abu Sa'id pressured him to execute Coban, he obeyed. Soon afterwards Ghiyathu'd-Din himself died, in 1329. He left four sons: Shamsu'd-Din, Hafiz, Mu'izzu'd-Din Husain, and Baqir. Shamsu'd-Din, who succeeded him, died shortly after; Hafiz, a scholar and the next person to take the throne, was murdered after two years. The succession therefore fell on Mu'izzu'd-Din.

Four years after Mu'izzu'd-Din's ascension, the Ilkhan Abu Sa'id died, following which the Ilkhanate quickly fragmented. Mu'izzu'd-Din, for his part, allied with Togha Temur, a claimant to the Ilkhanid throne, and paid tribute to him. Up until his death, Mu'izzu'd-Din's main concern were the neighboring Sarbadars, centered in Sabzavar. As the Sarbadars were the enemies of Togha Temur, they considered the Kartids a threat and invaded. When the Kartids and Sarbadars met in battle at Zava on July 18, 1342, the battle was initially in the favor of the latter, but disunity within the Sarbadar army allowed the Kartids to emerge victorious. Thereafter, Mu'izzu'd-Din undertook several successful campaigns against the Chagatai Mongols to the northeast. During this time, he took a still young Timur into his service. In 1349, while Togha Temur was still alive, Mu'izzu'd-Din stopped paying tribute to him, and ruled as an independent sultan. Togha Temur's murder in 1353 by the Sarbadars ended that potential threat. Sometime around 1358, however, the Chagatai amir Qazaghan invaded Khurasan and sacked Herat. As he was returning home, Qazaghan was assassinated, allowing Mu'izzu'd-Din to reestablish his authority.

Another campaign by the Sarbadars against Mu'izzu'd-Din in 1362 was aborted due to their internal disunity. Shortly afterwards, the Kartid leader welcomed Shi'i dervishes fleeing from the Sarbadar ruler 'Ali-yi Mu'ayyad, who had killed their leader during the aborted campaign. In the meantime, however, relations with Timur became tense when the Kartid launched a raid into his territory. Upon Mu'izzu'd-Din's death in 1370, his son Ghiyas al-Din Pir 'Ali inherited most of the Kartid lands, except for Sarakhs and a portion of Quhistan, which Ghiyas al Din's stepbrother Malik Muhammad gained.

Ghiyas al-Din, a grandson of Togha Temur through his mother Sultan Khatun, attempted to destabalize the Sarbadar state by stirring up the refugee dervishes within his country. 'Ali-yi Mu'ayyad countered by conspiring with Malik Muhammad. When Ghiyas al-Din attempted to remove Malik Muhammad, 'Ali-yi Mu'ayyad flanked his army and forced him to abort the campaign, instead compromising with his stepbrother. The Sarbadars, however, soon suffered a period of internal strife, and Ghiyas al-Din took advantage of this by seizing the city of Nishapur around 1375 or 1376. In the meantime, both Ghiyas al-Din and Malik Muhammad had asked for the assistance of Timur regarding their conflict: the former had sent an embassy to him, while the latter had appeared before Timur in person as a requester of asylum, having been driven out of Sarakhs. Timur responded to Ghiyas al-Din by proposing a marriage between his niece Sevinj Qutluq Agha and the Kartid ruler's son Pir Muhammad, a marriage which took place in Samarkand around 1376.

Later on, Timur invited Ghiyas al-Din to a council so that the latter could submit to him, but when the Kartid attempted to excuse himself from coming by claiming he had to deal with the Shi'i population in Nishapur, Timur decided to invade. He was encouraged by many Khurasanis, included Mu'izzu'd-Din's former vizier Mu'in al-Din Jami, who sent a letter inviting Timur to intervene in Khurasan, and the shaikhs of Jam, who, being very influential persons, had convinced many of the Kartid dignitaries to welcome Timur as the latter neared Herat. In April 1381 Timur arrived before the city, whose citizens were already demoralized and also aware of Timur's offer not to kill anyone that did not take part in the battle. The city fell, its fortifications were dismantled, theologians and scholars were deported to Timur's homeland, a high tribute was enacted, and Ghiyas al-Din and his son were carried off to Samarkand. Ghiyas al-Din was made Timur's vassal, until he supported a rebellion in 1382 by the maliks of Herat. Ghiyas al-Din and his family were executed around 1383, and Timur's son Miran Shah destroyed the revolt. That same year, a new uprising led by a Shaikh Da'ud-i Khitatai in Isfizar was quickly put down by Miran Shah. The remaining Kartids were murdered in 1396 at a banquet which Miran Shah had invited them to. The Kartids therefore came to an end, having been the victims of Timur's first Persian campaign.