Their journeys have all been very different.
Virgil van Dijk arrived at Liverpool amid a flurry of flashbulbs after becoming the most expensive defender on the planet.
His current centre-back partner Joel Matip didn't cost a penny after signing as a free agent from Schalke three years ago.
Left-back Andy Robertson has enjoyed a remarkable rise after being plucked from relegated Hull City for just £10million.
Injury update as Liverpool warned to expect surprise at Southampton
On the other flank, exciting youngster Trent Alexander-Arnold has made the giant leap from promising Academy graduate to first-team regular.
Put together, they form a commanding backline which is the most miserly in the Premier League. In 32 league matches, the title-chasing Reds have conceded just 19 goals.
This title challenge is built on firm foundations and Jurgen Klopp believes the diversity of his defensive personnel is a real strength for the Reds.
With Van Dijk and Matip aged 27, Robertson 25 and Alexander-Arnold 20, the manager insists they are only going to get better.
“The best way would be we don't have to do a lot (in the transfer market) because the age group of the players is brilliant,” Klopp said.
“They all have a long career ahead which is cool and how it looks at the moment is that they want to spend the majority of their careers here which is cool as well.
The Premier League transfer changes that will save Liverpool millions in the market
“Having different characters always helps, if you are all mainstream, all the same way, that it difficult. It is just nice to see.
“It is not important how much you cost or how big the price was. Virgil came here and it was a big step for him.
“He knew he could improve, he wants to improve, he was at Celtic and could win titles there, but this is the first club really where.... He sees his future here now. Let's try everything possible to be successful.
“It was exactly the same for Robbo. It is not important if you are £7million, £8million, £10million. Joel was the same and he was on a free transfer.
“Trent dreamed of nothing else since he was born of being involved in something like this and that is all good. It is all different ideas and different characters. Joe (Gomez) is the same and he's finally fit again as well.
Liverpool's successful summer transfer trend - and who they could target next
“It is probably not the most expensive defence in the world but it is a proper one, a really proper one. Wherever good players are coming from, wherever they are raised, wherever the dream started, they are welcome here at Liverpool.
“Now it feels to me like we have a proper bunch of players together, not only the defence. They really stick to each other and the club is in a way which is exceptional. They want to do the job 100%.”
