The first Panda (type 141) 4x4 is from 1983, just a couple of years after the Pandas launch in 1980 and was just called the "Panda 4x4".
This model Panda was redesigned a few years later and the special addition "Sisley 4x4" was added along side the "Panda 4x4".
The Sisley became popular, so Fiat added it as a proper model a year or so later.
(Sisley are a clothing company, and this isn't the only Panda model to wear a clothing company's label, Fiat launched the K-Way special edition a few years ago, though not in the UK and on a FWD Panda)
A couple of years after this, around 1991, the Panda got a refresh again (Cats and EFI became available) and the 4x4 became the "Trekking 4x4".
Although Fiat dropped the Panda from the UK price list a few years after, they pretty much carried on in Italy like this until 2003.
The next gen Panda (169) came along in 2003 and was soon available with 4x4 as the "Climbing" with the FIRE 1.2 petrol engine in the UK.
A few years later (2008/9) came the Panda "Cross" 4x4 with the Multijet diesel engine, actual date depends on market, but I believe they launched the "Climbing" with diesel power in Italy around the same time or just before.
The latest gen Panda (312/319) came in 2011 and the 4x4 model came a year later.
It's just called the "4x4" with both Twinair petrol and Multijet diesel available.
Fiat reused the "Trekking" name again around this time, they used it on a Panda with a jacked up 4x4 stance and body cladding, but with just front wheel drive. (later quietly dropped for some reason?)
2013 saw the "Antarctica" special edition, launched to mark 30 years of 4x4 Pandas.
(worth noting for those not familiar with Italian special editions/marketing. If 200 are launched, this doesn't mean only 200 were built, but that 200 were built for every market!)
I think Austria, home of Steyr got their own 4x4 special at this time though.
Then in 2014 came the (new) Panda "Cross" model with 4x4, again with Twinair and Multijet diesels, but offered with slightly more power.