Question:  Dragon's Hall is a supplement for fantasy role-playing games published by a commpany active since what year?

Context paragraphs:
Dark Folk (Mayfair Games): Dark Folk is a supplement for fantasy role-playing games published by Mayfair Games in 1983.

Fantastic Treasures II: Fantastic Treasures II is a supplement for fantasy role-playing games published by Mayfair Games in 1985.

Dragon's Hall: Dragon's Hall is a supplement for fantasy role-playing games published by Judges Guild in 1981.

Wizards (Mayfair Games): Wizards is a supplement for fantasy role-playing games published by Mayfair Games in 1983.

Dwarves (Mayfair Games): Dwarves is a supplement for fantasy role-playing games published by Mayfair Games in 1982.

Elves (Mayfair Games): Elves is a supplement for fantasy role-playing games published by Mayfair Games in 1983.

Dragons (Mayfair Games): Dragons is a supplement for fantasy role-playing games published by Mayfair Games in 1986.

Judges Guild: Judges Guild is a game publisher that has been active since 1976.  The company created and sold many role-playing game supplements, periodicals and related materials, but became best known during the late 1970s and early 1980s as one of the leading publishers of "Dungeons & Dragons" related materials.  Its flagship product, "City State of the Invincible Overlord", was the first published RPG supplement to feature a fully developed city environment.  The supplement was followed closely by numerous ancillary cities, maps, and other materials published by Judges Guild.

Fantastic Treasures: Fantastic Treasures is a supplement for fantasy role-playing games published by Mayfair Games in 1984.

Witches (Mayfair Games): Witches is a supplement for fantasy role-playing games published by Mayfair Games in 1990.

Supporting paragraphs: Dragon's Hall Judges Guild
Answer: 1976