Istrouma is an Imperial Desert World and Space Marine Chapter Homeworld of the Tome Keepers Space Marine Chapter located in the Macharius Alpha Sector of the Segmentum Pacificus.
Istrouma exists in a state of perpetual suffering. Scoured by baleful energy from the system's white dwarf star, the planet's surface is heavily irradiated, save for a single large continent that survives on the dark side of the world away from the star's harsh glare. In addition, the planet's erratic orbit and the orbit of its two moons create upheaval that alernatively birth new mountain ranges or tear open the crust of the planet to reveal seas of molten lava.
Istrouma is sparsely inhabited by Imperial standards. Small colonies of miners exist out in the barren wilderness and deep beneath the mountain ranges, but the majority of the world's population lives on the one easily habitable continent. The capital city of Nivenah, beneath which can be found the vast libraries of the Istrouman people. The Fortress-Monastery of the Tome Keepers can be found towards the planet's northern range. It is heavily shielded to protect it from radiation.
The inhabitants of Istrouma live very short lifespans due to the planet's harsh conditions. In effect, progress in their society is painfully slow due to people dying at a young age before they can reach their full potential. This forces the Istrouman people to learn their craft quickly so that they can contribute to society before they expire, and there is precious little time to pass on that knowledge from master to apprentice, from one generation to the next. For this reason, in place of oral traditions and effective mentorship, the people of this world have written records of everything. When death takes a person, these records enable their successor to continue where they left off, if only for a few short years before they too must pass on the torch to the next scientist, artisan or strategist in line.
Each Istrouman records their deeds for posterity in their own personal or family book, essentially like a journal. This, combined with their life's work and their quest to record every bit of knowledge possible, creating a colossal amount of information worthy of filling many libraries. Once full, these completed tomes are then stored beneath the surface of the planet's capital within the planet's great archive libraries.
When the Ultramarines Successor Chapter, designated number 281 first landed upon Istrouma's surface, they were welcomed as heroes of legend. After being informed of the tragedy that had stricken the people of Istrouma and their greatly shortened lifespan, the Chapter was moved beyond words. The Space Marines were further honoured with the stewartship of the Istrouman people's most revered possession -- their vast libraries located beneath the surface of the planet's capital city. This vast libary was almost a city in its own right, and it contained millions upon millions of books, dataslates and information terminals. Upon those shelves lay the history of aeons. The Astartes graciously accepted this most profound gift and swore a solemn oath to protect it forevermore. Taking the name "Tome Keepers", they have proudly borne their Chapter name ever since.
Sources
- White Dwarf #458 (Nov-Dec 2020), "Index Astartes: Tome Keepers," pp. 46-59
- Warhammer Community - Index Astartes: The Tome Keepers! (13 Nov 2020)