GEOFF BENNETT: In Iraq, it's hard to find a town, a neighborhood, a street, or a family that hasn't been touched by the U.S. invasion 20 years ago and its turbulent aftermath, but some parts of the country suffered especially hard under the repeated waves of violence, loss and trauma.

Special correspondent Simona Foltyn tells the story of the last two decades through the eyes and memories of two families.

SIMONA FOLTYN: Twenty years later, Dhahi Kareem still recalls his first encounter with American troops like it was yesterday.

DHAHI KAREEM, Resident of Iraq (through translator): The Americans came, and they wanted to buy something from my shop.

I refused to deal with them.

They attacked me and hit me here.

More than four or five soldiers attacked me.

I had a broken rib.

SIMONA FOLTYN: There's only a small scar left on his cheek from that incident, but the wounds left by the American invasion and its aftermath run deep in this community.

DHAHI KAREEM (through translator): We were hoping that, even if the matter ends with the occupation of the Americans, at least there will be a semblance of security, but, unfortunately, things only got worse and worse.

SIMONA FOLTYN: Dhahi originally hails from the Sunni area of Jurf Al Sakhar 50 miles south of the capital, Baghdad.

It's part of what used to be called the Triangle of Death, a cauldron of frequent attacks on American forces by armed groups, including by al-Qaida.

DHAHI KAREEM (through translator): It really was the Triangle of Death.

You left in the morning, and you didn't know if you'd come back home.

SIMONA FOLTYN: Dhahi was a low-level member of Saddam's Baath Party and initially supported the Sunni insurgency, before it was taken over by al-Qaida.

DHAHI KAREEM (through translator): In the beginning, there was strong sympathy with the resistance, when it wasn't yet al-Qaida, because they were hitting the Americans.

But the Americans had armored vehicles, so the biggest death toll was among the Iraqis.

SIMONA FOLTYN: Both Sunni and Shia civilians were caught in the middle.

Further south in the town of Twareej, we meet Jebel Abdel Amir.

He used to work as a minibus driver and often took passengers on the dangerous journey through the Triangle of Death.

JEBEL ABDEL AMIR, Resident of Iraq (through translator): There were so many victims in this area.

SIMONA FOLTYN: But one incident remains etched in his memory.

An American military convoy opened fire on his own family while they were driving down this road.

JEBEL ABDEL AMIR (through translator): We were driving very slowly.

The American soldier got angry at us.

He waved us away, and the one behind him opened fire.

SIMONA FOLTYN: His family sustained only minor injuries.

but it was another rude awakening that the so-called liberation wasn't going to simply end decades of brutality and hardship.

Twareej is a Shia town.

And many members of Jebel's extended family had opposed the Sunni dictator.

Jebel's wife, Suheila, lost five relatives to Saddam's repression.

She shows me a picture of her brother, who was arrested and executed in 1989.

SUHEILA SHAMKHI, Resident of Iraq (through translator): Here he is standing in the market with a friend.

This was one week before he was arrested.

SIMONA FOLTYN: Suheila initially welcomed the American invasion.

SUHEILA SHAMKHI (through translator): We thought the Americans would free us from Saddam, that, finally, we would get our rights.

But we haven't seen any benefit.

SIMONA FOLTYN: Regime change happened quickly, but there was no plan purposefully for the day after.

GEORGE W. BUSH, Former President of the United States: The United States and our allies have prevailed.

SIMONA FOLTYN: The Coalition Provisional Authority, the American governing body that took over the country, had little knowledge of Iraq.

In a misguided attempt to purge Saddam loyalists, it dismantled the Iraqi army and other state institutions.

Jebel served as a soldier in the army and was fired.

JEBEL ABDEL AMIR (through translator): The biggest mistake the Americans committed was to dissolve the military and state institutions, because those were the ones who controlled the streets and all matters.

Yes, it was a harsh system, but a system is nonetheless a system.

SIMONA FOLTYN: Extremists and insurgents, both Sunni and Shia, filled the security vacuum and mobilized against the occupiers.

They soon began turning on one another.

After the 2006 bombing of the Shia shrine in Samarra, the country descended into a violent sectarian civil war between Sunnis and Shias.

Hundreds of thousands were killed.

Mixed areas, like the town of Musayyib, where Dhahi now lives, saw the worst of it.

DHAHI KAREEM (through translator): If people were killed from one side, then people were killed from the other side.

Whether you had anything to do with it or not, you had to pay the price.

SIMONA FOLTYN: The sectarian war began to subside in 2008.

American troops withdrew in 2011.

But the forces that were unleashed in 2003 were not easily subdued.

Al-Qaida morphed into ISIS, and American troops returned in 2014 to take part in the war, when the jihadists conquered a third of Iraq's territory.

In the Triangle of Death and elsewhere in Iraq, ISIS' brutal reign reignited intercommunal tensions.

Three of Dhahi's cousins were kidnapped in 2014 and are still missing.

He blames Shia armed groups for their disappearance.

DHAHI KAREEM (through translator): They were innocent people who have no relations to politics or religion.

They were kidnapped just because they were Sunni.

SIMONA FOLTYN: The repeated cycles of violence caused massive waves of displacement, resulting in enduring demographic changes.

Dhahi's family fled their 12-acre farm in his original home area of Jurf Al Sakhar, located a short drive from here.

He hasn't been back since 2006.

DHAHI KAREEM (through translator): If I tried to return to my farm, I don't think I'd come back alive.

Entry to the area is forbidden.

SIMONA FOLTYN: Jurf Al Sakhar is now controlled by a powerful Shia armed group that mobilized against the American occupation.

It later fought ISIS as part of an umbrella of Shia-led paramilitaries that have since been integrated into the state security services.

Dhahi cannot cross this checkpoint.

We stop at a market just a few yards away.

Many of the men who work here are also displaced from Jurf Al Sakhar.

Their fate is part of the series of incidents that can be traced back to the invasion.

DHAHI KAREEM (through translator): This is one of the results of the American invasion.

The United States bears the responsibility.

SIMONA FOLTYN: The armed actors who rose up after 2003 later used their military might to consolidate their grip on politics and the economy.

Even after the violence subsided, ordinary Iraqis didn't taste the dividends of democracy.

Saddam's repressive dictatorship was replaced with a dysfunctional kleptocracy.

And little of Iraq's oil wealth trickled down to the population.

Jebel and Suheila are equally disappointed with Iraq's ruling elites.

JEBEL ABDEL AMIR (through translator): There are huge resources in Iraq, but, because of the corrupt elites, the people are not getting their share.

SIMONA FOLTYN: The couple have one daughter, Asma, and five sons, including Mohammed.

They struggled to find jobs until the war against ISIS raised the demand for young men.

Both Mohammed and another son, Ali, joined the Iraqi army.

It was the only chance to find a stable job.

MOHAMMED JEBEL, Resident of Iraq (through translator): The economy was doing poorly, and I didn't have a high school degree.

So, there was no other chance but to join the army.

SIMONA FOLTYN: Another war imposed another layer of loss and trauma.

Entire busloads of young men were shipped to the front lines in 2014.

The pictures of the fallen now line the streets of Twareej and other cities across Iraq.

Mohammed lost five of his colleagues when ISIS attacked their convoy.

MOHAMMED JEBEL (through translator): Most of my friends have died.

We were 31 in my sniper unit.

With one explosion, an entire Humvee was taken out.

SIMONA FOLTYN: ISIS was declared defeated in 2017, though sleeper cells continue to destabilize rural communities.

It is why some of the Shia paramilitaries say their continued presence in places like Jurf Al Sakhar is required.

Dhahi now lives on a much smaller plot of land he inherited from his late father.

He has given up hopes of reclaiming his farm.

DHAHI KAREEM (through translator): The situation will not stabilize.

The area was exposed to killing, dispossession, and many other problems.

SIMONA FOLTYN: For now, the guns have fallen silent.

But the repeated cycles of violence have irrevocably marked this community.

Iraq remains a fractured nation awash in weapons and still struggling to find peace.

For the "PBS NewsHour," I'm Simona Foltyn south of Baghdad.

GEOFF BENNETT: And there's much more about the anniversary of the Iraq invasion online, including insights from foreign affairs correspondent Nick Schifrin about the challenges that young Iraqis are facing 20 years later.

That is on our TikTok account.