Before the Taleban lost their positions in the Taiwara region in late July, the recent resistance phenomenon was not only the Afghan government, but also the local people who had gathered around their representative in parliament.

The small Afghan commando unit has already been routed in Taiwara, located in the western part of the isolated Gore district. Ibrahim Malik Zada, a provincial MP and anti-Taliban fighter since the 1990s, has arrived from Kabul in an attempt to mobilize Final defense of the city.

Malik Zada said the Afghan commandos, backed by the Afghan air force and the United States, had backed Tewara. It shows the fall and recapture of the region and how to face that long war. He added that "Unregulated territory throughout the province continues to increase as each side - whether government or armed - mobilizes resources and gains control over a single area for a short time. However, neither side seems to be able to capture the land it receives.

Dozens of civilians and militia forces were killed in northern Afghanistan in what officials on Sunday described as an attack by Taliban fighters teamed up with a commander claiming allegiance to the Islamic State. If true, the open cooperation between the militant groups, which have sometimes fought turf battles in the past, could be further trouble for the struggling Afghan government.

Sayad district, in northern Sar-e-Pul province, had put up a fierce defense over the past two years against attacks by insurgents as other parts of the province seemed to be buckling under Taliban pressure. Several local officials say the Taliban joined forces with Sher Mohammed Ghazanfar, a local commander claiming allegiance to the Islamic State, to overrun the Mirza Olang area. Then he turned to blocking local militiamen, as well as civilians, from fleeing.

“According to our credible information, 50 people have been killed,” said Sharif Aminyar, the district governor of Sayad. Mr. Aminyar said 18 of the people killed had been members of the Afghan Local Police, a government militia, and other local militias on the government payroll. The rest were civilians.

“It was a joint Daesh and Taliban operation,” Mr. Aminyar said, using the Arabic name for the Islamic State, which is also known as ISIS or ISIL. “The Taliban were led by Mullah Nader and Daesh was led by Sher Mohammed Ghazanfar.”

“Despite several demands for air support and the special forces,” he said, “the demands were ignored by central government. They told us the air force was busy in other provinces.” Zabihullah Mujahid, a spokesman for the Taliban, denied any cooperation with the Islamic State on the operation and said local residents had misunderstood. “Ghazanfar is not Daesh — he is our commander in Sar-e-Pul, a very active commander, and he is under our command, our flag,” he said. “He has allegiance with us.”

Mr. Mujahid denied allegations of civilian casualties, and said only militiamen had been killed.

Residents described a government effort over several days to try to evacuate people, a task that became impossible after militants overran the area.

Abdul Qadir, 25, said he had managed to escape with his mother, wife and two children. But his father and brother were not so lucky. Mr. Qadir lost a leg years ago, and he rode his family’s donkey, with his two children tied to his back, he said.

“I lost my brother and father,” Mr. Qadir said. “Now I have to take care of three families — my father’s family, my brother’s family and my own family.”

While the Taliban have been resurgent around the country, exerting increasing pressure in previously safe areas of the north, the Islamic State threat has largely remained contained. The group has been targeted by the Afghan Army and United States air power in its stronghold, the Achin district in Nangarhar province. But other, smaller pockets claiming Islamic State affiliation have also popped up in other parts of the country.

While the Taliban and fighters affiliated with the Islamic State have fought turf battles in the east, officials have long said the groups’ interactions in the north have been more complex, with the two often having a symbiotic relationship. Intelligence and security officials have expressed uncertainty over whether what operates as the Islamic State in parts of Afghanistan is really tied to the group’s headquarters in Syria and Iraq at all, or if it is just the Taliban and other militant groups with a new identity.