What were the most prominent tribulations (fitan) that occurred during the era of the Rightly Guided Caliphs, and what are the reliable references that discuss this topic in detail?

We apologize for not answering the question due to being occupied with other questions. We direct the questioner to references for research, including history books such as: "Al-Bidaya wa Al-Nihaya" (The Beginning and the End) and "Islamic History," as well as creed books related to the Companions, and Sunnah books like the two Sahihs (Bukhari and Muslim) in the chapters on tribulations (fitan) and the virtues of the Companions, in addition to books that refute slanders, such as: "Al-Awasim min Al-Qawasim" (The Protections from the Disasters) and "Minhaj As-Sunnah" (The Path of the Sunnah) and "Shubuhat Ar-Rafidah Hawla As-Sahaba" (Shiite Doubts about the Companions) and "Al-Fitnah fi Ahad Al-Khulafa’ Ar-Rashidin" (The Tribulation in the Era of the Rightly Guided Caliphs), and the book "Huqba min At-Tarikh" (An Era from History).