seyoungsong/Open-Korean-Historical-Corpus

Open Korean Historical Corpus

Dataset Description

The Open Korean Historical Corpus is a large-scale, openly licensed dataset created to address the lack of accessible data for Korean NLP and historical linguistics.

It contains 17.7 million documents (5.1 billion tokens) compiled from 19 distinct archives, spanning 1,300 years from the 7th century to 2025. The corpus is linguistically diverse, covering Korean (Middle, Early Modern, Modern, North), Classical Chinese, and Japanese. It provides the first large-scale, open resource for under-represented writing systems like Korean-style Sinitic (Idu) and Hanja-Hangul mixed script.

Paper: https://arxiv.org/abs/2510.24541

Data Sample

{
  "id": "news_archive:CNTS-00093108108",
  "text": "昨日內部에셔 郡守奏本을 奉呈얏더라",
  "content": {
    "body": "昨日內部에셔 郡守奏本을 奉呈얏더라",
    "title": "郡奏三度"
  },
  "year": 1905,
  "language": "Modern Korean",
  "script": "Hanja, Old Hangeul",
  "source": "National Library of Korea",
  "corpus": "Korean Newspaper Archive",
  "copyright": "Public Domain",
  "url": "https://www.nl.go.kr/newspaper/detail.do?content_id=CNTS-00093108108",
  "format": "{body}",
  "metadata": {
    "host_ko": "대한매일신보",
    "year_str": "西曆一千九百五"
  },
  "analytics": {
    "text_length": 19,
    "content_body_length": 19,
    "content_title_length": 4
  }
}

Intended Use

This corpus is intended for:

• Quantitative diachronic analysis of the Korean language.
• Pre-training or fine-tuning Large Language Models (LLMs) on historical and diverse Korean scripts.
• Research in historical NLP, digital humanities, and Korean linguistics.

Code Repository

The code used for preprocessing, language/script identification, and classification (including the Idu classifier) is available on GitHub:

• GitHub: https://github.com/seyoungsong/OKHC

Citation

@article{song2025open,
  author  = {Seyoung Song and Nawon Kim and Songeun Chae and Kiwoong Park and Jiho Jin and Haneul Yoo and Kyunghyun Cho and Alice Oh},
  journal = {ArXiv preprint},
  title   = {Open Korean Historical Corpus: A Millennia-Scale Diachronic Collection of Public Domain Texts},
  url     = {https://arxiv.org/abs/2510.24541},
  volume  = {abs/2510.24541},
  year    = {2025}
}