---
title: "HistoricalPeriod"
language: "en"
type: "Entity"
summary: "Notable historical periods in world history."
canonical_url: "https://reference.wolfram.com/language/ref/entity/HistoricalPeriod.html"
source: "Wolfram Language Documentation"
related_guides: 
  - 
    title: "Entity Types"
    link: "https://reference.wolfram.com/language/guide/EntityTypes.en.md"
---
# HistoricalPeriod

Notable historical periods in world history.		[Related Interpreter](https://reference.wolfram.com/language/ref/interpreter/HistoricalPeriod.en.md)

Entity["HistoricalPeriod", name] or Entity[...] represents an entity of type "HistoricalPeriod".

Entity[...][prop] gives the value of a specified property.

Entity[...][{propi, …}] gives the value of a list of properties.

Entity[...][Dated[prop, date]] gives the value of a property associated with a particular date specification.

EntityClass["HistoricalPeriod", {propi -> speci, …}] represents a class of entities with values of propi defined by speci.

## Sample Entities

* Entity["HistoricalPeriod", "AfsharidDynasty"]Entity["HistoricalPeriod", "InitialPeriod"]Entity["HistoricalPeriod", "JoseonDynasty"]Entity["HistoricalPeriod", "LiaoDynasty"]Entity["HistoricalPeriod", "NaraPeriod"]Entity["HistoricalPeriod", "OldKingdom"]Entity["HistoricalPeriod", "SamanidDynasty"]Entity["HistoricalPeriod", "SpaceAge"]Entity["HistoricalPeriod", "TahiridDynasty"]Entity["HistoricalPeriod", "TaishoPeriod"]**…**

## Properties

|                   |                  |
| ----------------- | ---------------- |
| CountriesInvolved | areas involved   |
| EndDate           | end date         |
| EntityClasses     | entity classes   |
| EntityTypeList    | entity type list |
| Name              | name             |
| PeopleInvolved    | people involved  |
| StartDate         | start date       |

## Details

* ``"HistoricalPeriod"`` entities represent notable named periods in history.

* Some properties are available for the ``"HistoricalPeriod"`` entity type as a whole and can be given using the form ``EntityValue["HistoricalPeriod", property]``. Such properties include:

|                               |                                                                    |
| ----------------------------- | ------------------------------------------------------------------ |
| "Properties"                  | the list of available properties                                   |
| "PropertyCanonicalNames"      | the standard names of available properties                         |
| "SampleEntities"              | a sample list of available entities (typically of length 10)       |
| "SampleEntityClasses"         | a sample list of available entity classes (typically of length 10) |
| "EntityCount"                 | number of entities available                                       |
| "Entities"                    | the list of available entities                                     |
| "EntityCanonicalNames"        | the standard names of available entities                           |
| "EntityClasses"               | the list of available entity classes                               |
| "EntityClassCanonicalNames"   | the standard names of available entity classes                     |
| "PropertyClasses"             | the list of available property classes                             |
| "PropertyClassCanonicalNames" | the standard names of available property classes                   |
| "PropertyCount"               | number of properties available                                     |

* The following annotations can be used in the third argument of ``EntityValue["HistoricalPeriod", property, annotation]`` :

|     |     |
| --- | --- |
| "Source" | source information for the property |
| "Date" | the date associated with the entity-property value (if any) |
| "EntityAssociation" | an association of entities and entity-property values |
| "PropertyAssociation" | an association of properties and entity-property values |
| "EntityPropertyAssociation" | an association in which the specified entities are keys, and values are a nested association of properties and entity-property values |
| "PropertyEntityAssociation" | an association in which the specified properties are keys, and values are a nested association of entities and entity-property values |
| "Dataset" | a dataset in which the specified entities are keys, and values are an association of property names and entity-property values |

* The following annotations can be used in the second argument of ``EntityValue[property, annotation]`` :

|                          |                                                                 |
| ------------------------ | --------------------------------------------------------------- |
| "Qualifiers"             | the list of possible qualifiers for the property                |
| "QualifierValues"        | the list of possible values that can be given to each qualifier |
| "DefaultQualifierValues" | the list of default values for the property's qualifiers        |
| "Description"            | a brief textual description of the property                     |
| "Definition"             | a detailed textual definition of the property                   |
| "PhysicalQuantity"       | the physical quantity associated with the entity-property value |
| "Unit"                   | the unit associated with the entity-property value              |

* A qualifier value of ``Automatic`` indicates that an applicable format of values can be used; e.g. for the ``"Date"`` qualifier, this includes a proper date or date span.

---

## Examples (4)

### Basic Examples (4)

Use ctrl+= for entity discovery:

```wl
In[1]:= \[FreeformPrompt][" Renaissance "]

Out[1]= Entity["HistoricalPeriod", "EuropeanRenaissance"]
```

---

Find a property value for an entity:

```wl
In[1]:= Entity["HistoricalPeriod", "SpaceAge"]["StartDate"]

Out[1]= DateObject[{1957}, "Year"]
```

---

Retrieve a dataset of all available properties for an entity:

```wl
In[1]:= Entity["HistoricalPeriod", "EarlyMiddleAges"]["Dataset"]

Out[1]=
Dataset[Association[EntityProperty["HistoricalPeriod", "CountriesInvolved"] -> 
   {Entity["GeographicRegion", "Europe"], Entity["HistoricalCountry", "WesternRomanEmpire"], 
    Entity["HistoricalCountry", "ByzantineEmpire"]}, 
  EntityProperty["Hi ... lPeriod"]}, 
  EntityProperty["HistoricalPeriod", "Name"] -> "Early Middle Ages", 
  EntityProperty["HistoricalPeriod", "PeopleInvolved"] -> Missing["NotAvailable"], 
  EntityProperty["HistoricalPeriod", "StartDate"] -> DateObject[{400}, "Year"]]]
```

---

Find historical periods involving the Roman Empire:

```wl
In[1]:= EntityClass["HistoricalPeriod", "CountriesInvolved" -> MemberQ[Entity["HistoricalCountry", "RomanEmpire"]]]//EntityList

Out[1]= {Entity["HistoricalPeriod", "EuropeanMigrationPeriod"], Entity["HistoricalPeriod", "PaxRomana"]}
```

## See Also

* [`HistoricalEvent`](https://reference.wolfram.com/language/ref/entity/HistoricalEvent.en.md)
* [`HistoricalCountry`](https://reference.wolfram.com/language/ref/entity/HistoricalCountry.en.md)
* [`HistoricalSite`](https://reference.wolfram.com/language/ref/entity/HistoricalSite.en.md)
* [`HistoricalPeriod`](https://reference.wolfram.com/language/ref/interpreter/HistoricalPeriod.en.md)
* [`ComputedHistoricalPeriod`](https://reference.wolfram.com/language/ref/interpreter/ComputedHistoricalPeriod.en.md)

## Related Guides

* [Entity Types](https://reference.wolfram.com/language/guide/EntityTypes.en.md)

## History

* [Introduced in 2019 (12.0)](https://reference.wolfram.com/language/guide/SummaryOfNewFeaturesIn120.en.md)