Best materials for a long-lasting scroll
We actually have a good idea of which scroll materials last for hundreds of years, because we have scrolls that are hundreds of years old. What are they made of?

Parchment

We have two thousand year old scrolls written on parchment (as required for Jewish Torah scrolls). These seem to be mainly written using ordinary carbon black ink, but many (particularly Medieval) documents were written using Iron Gall black ink, of which many survive.

Parchment is expensive and relatively difficult to come by, but is still produced in small quantities.

Papyrus

The Egyptians wrote on papyrus scrolls, and we have several surviving examples including some over 3500 years old. Like the Jewish parchments, these were normally written using carbon black ink. 

Papyrus is also expensive, but not as expensive as vellum and more widely available.

Paper

We have surviving fragments of paper with writing/drawing on it from the 2nd century BC, and we know that the Chinese made scrolls from this material. Chinese painting normally used water based inks for both paper and silk scrolls.

Silk

Chinese scrolls have been written on silk for thousands of years - the excavations at Mawangdui unearthed silk scrolls dating back to the 2nd century BC. 

Silk fabric is readily available (if relatively expensive), but requires treatment before it can be written on.

Suggestion

Given the difficulty of acquiring and preparing the other substances, I'd suggest you look for paper. The specific type you're looking for is probably a relatively heavy acid-free paper (AKA archival paper or museum grade paper), which is specifically designed to last for a long time. 

As for ink, since you only seem to wish to write and not draw/paint in colour, I suggest the ubiquitous carbon black.