Warning: This article contains SPOILERS for The Walking Dead: Dead City season 2, episode 1, "Power Equals Power".With The Walking Dead's timeline has been complicated to keep track of ever since season 1, but with more and more spinoff shows being produced, things have only gotten harder. Despite seasons 1-8 taking eight years to produce, the events all happened within just a few years in the show, before season 9 introduced a six-year time skip.

Since then, more time has ed, with season 11's ending taking place around 13 years after the outbreak started. Daryl Dixon and The Ones Who Live both seem to occur shortly after the main show's conclusion; however, Dead City's timeline is much more complicated to follow. On the surface, it seemed like the spinoff might take place alongside The Walking Dead's other ongoing projects, but Hershel's age alongside some small clues confirmed that Dead City takes place further into the future, and a minor detail from season 2's finale revealed a new way to track time in the zombie universe.

"PDI" Seems To Be The Walking Dead's New System For Measuring Years After "AD"

The Bricks Had A Sign That Mentioned The Community Was "Founded 17 P.D.I."

Despite the characters never addressing it, a sign in front of the Bricks' entrance has the phrase "Founded 17 P.D.I" written on it, which seems to be the new system for measuring how many years have ed since the outbreak. Although the community seemed to be thriving in season 11, Hilltop relocated after The Walking Dead's ending, as it was too badly damaged to fully recover from the Whisperer War. Dead City season 1 revealed that Hilltop became the Bricks, but other than a few glances, we never saw much of the settlement until season 2's premiere.

The exact meaning of P.D.I. was never revealed, but it seems obvious it is referring to how many years have ed since the outbreak started.

Alongside explaining that the Bricks was part of the New Babylon Federation, we saw details about the place, such as its infrastructure, residents, and when it was founded. The exact meaning of P.D.I. was never revealed, but it seems obvious it is referring to how many years have ed since the outbreak started, the same way we use systems like AD and BC. Whereas communities like Alexandria and the Commonwealth never really measured time, New Babylon invented its own system to identify when this new world started and clearly has a way of tracking each year.

Benjamin Pierce's brief introduction showed he was obsessed with history as well as recording new developments, something Governor Charlie Byrd seemed to ire. Therefore, documenting key details about life since the apocalypse seems to be important to New Babylon, making it no surprise they found a way to keep up with time, hence the sign at the Bricks' entrance.

What "PDI" Could Actually Stand For In The Walking Dead's World

It Is Likely An Abbreviation For The Period After The Outbreak Started

P.D.I. is clearly an abbreviation for whatever New Babylon has called this measure of tracking years, but there is no confirmation as to what it really stands for. My best guess would be something along the lines of "Post Dead Insurrection" or "Post Dead Insurgence", but it could also be something far less obvious. Given things like AD and BC are Latin, "PD" could refer to "per diem" which means "by the day", but the "I" remains a mystery if that theory is true.

Most likely, the system is some sort of direct reference to life since the dead started rising, but without knowing too much about New Babylon, it's hard to really theorize how they'd choose to describe the world since then. Considering Dead City season 1's ending teased a big role for New Babylon and season 2's plot centers around their expedition to Manhattan, it seems certain we will find out more about them, and with any luck, the spinoff series may actually reveal what this ambiguous phrase stands for.

What The Walking Dead: Dead City Season 2's Premiere Reveals About The Spinoff's Timeline

Dead City Season 2 Takes Place Several Months After Season 1 & Presumably 6 Years After The Walking Dead Season 11

Dead City season 2's first episode may have kept the meaning of P.D.I. hidden, but it revealed plenty about the show's timeline. Perhaps most importantly, Negan's conversation with the Dama in "Power Equals Power" indicated that several months had ed between season 1's finale and season 2's premiere. As the Dama and the Croat laid out their plans, Negan claims "I feel like we had this conversation a couple of months ago", suggesting that it has been at least two months since the duo were first introduced.

Additionally, the Bricks' sign also hints that at least 17 years have ed since The Walking Dead's apocalypse started, meaning we have a more definitive idea about when the show takes place. Previously, Dead City's setting was always speculation, but we knew it was further into the timeline than the other spinoffs. Now, we can confidently say that the Brick was founded four years after season 11, which is a significant revelation.

The fact that the story is set much later than the other projects means we know Maggie, Negan, and Hershel all survive beyond where the rest of the franchise is currently. Likewise, it means Daryl Dixon will have to catch up with Dead City before any sort of Walking Dead crossover project can happen; otherwise, fans will have an even harder time trying to keep tabs on where the zombie universe is at, making season 2's premiere quietly important in of establishing a precise timeline.