One of the key differences between our modern life and the life of people who lived on the Earth in pre-modern times is in their stronger engagement with nature and natural phenomena. One of the reasons behind this difference certainly
is the fact that their life was more vulnerable to the things that happen around them in nature. In addition to this, there were less obstacles for the people of ancient and medieval times to directly observe these natural phenomena.
While we, as modern people, are suffering from the light pollution in modern cities that ban us from looking at the beautiful sky above our head, the sky was an accessible laboratory for the people of pre-modern world. This will
be immediately understood if we ask our friends to see how many of them, for example, have ever observed a common phenomenon like meteor shower.

The fact that the people of the pre-modern world were more attendant about natural phenomena is clear from the number of historical writings, from a diverse cultural background, that recorded these phenomena. Recording these natural
phenomena was a common practice in ancient and medieval Chinese, Egyptian, Babylonian, Byzantine, Islamic, and European historical writings. The importance of these records is not only a matter of history writing. These records provide
us with some firsthand observations that can help us to understand what has happened in our world in the past. They can possibly help us to collect information about different phases of climate changes on the Earth, or about the
regularity of earthquakes in different regions. They tell us how a phenomenon like solar activity was recorded in pre-modern times. Or we can calculate the orbits of comets based on long term observations.

Medieval historical chronologies commonly included reports of natural phenomena occurring on the Earth, in the atmosphere, or in the sky. Since the methods for recording these phenomena were not developed systematically, different
authors were engaged differently with the details of these phenomena in their records. Some of these phenomena were recorded by historians who had education in science, but some others did not. So, always, there is a possibility
that they confuse a celestial phenomenon with an atmospheric one. Another challenge is that many of the records found in historical writings were quoted, orally or in written, from another source. Considering the complexity of the
transmission of these records, there is a strong possibility that some errors were introduced in these records. One of the common consequences of this fact is that a very similar record is dated differently in different sources.

For the historians of science, the main challenge is to evaluate these records and extract the information that serves both historians and scientists. One thing that can help historians in their investigations of these records is comparing
the records in each source and in each historical context to the independent observations in other cultures and languages. For example, if we have the record of a comet in a Chinese source, and we find a similar record in an Islamic
or a Byzantine source, we can confirm that such an observation of comet was authentic.

There are some modern studies of celestial and terrestrial phenomena in which some historical data from some specific cultures were studied. But no attempt has been made to establish a universal database that can bring records from
different cultures to one place for researchers. In project CMGPHRD, we aim to present these records in the form of a digital platform that will allow scholars to study and investigate their accuracy. The records in the CMGPHRD are
selected from historical sources written in different languages, from Chinese and Korean to Arabic, Persian, Syriac, and Byzantine Greek. While the majority of the records are from original historical sources, available modern secondary
sources have been included in CMGPHRD as well. Phenomena like comet, meteor, meteorite, meteor shower, supernova, aurora, solar activity, eclipses, conjunctions, dusk, storm, dust, thunder, rain, and earthquake has been included
in the database. Until July 2023, the total number of entries reached 2500. Each entry in the database is designed to have a full bibliographical reference to the source from which the entry is created, a transcription of the record
in original language, an English translation of the record, an image clip of the record from the original publication, and the relevant secondary references. Dates of events are provided both in common era and original calendar system.
Nevertheless, some of the entries are still under compilation. The English translation of the records, for example, are being added to the database gradually.