The Ice warriors are a species of war-like alien. They previously lived on the planet Mars and ate Martian fish. When their home planet became too hot for them to live in, they moved to planets such as Peladon.
The Time Lords are the alien race which the Doctor belongs to. They have two hearts. They can avoid dying by "regeneration" (transforming their bodies). The Time Lords were in some episodes in the classic series. Sometimes they were allies of the Doctor (at one point he became their president). Other times they were enemies. The Time Lords came from the planet Gallifrey.
When the series returned in 2005, the Time Lords had disappeared in the "Time War". This was a very big war with the Daleks. The Doctor explained that he stopped the war by destroying Gallifrey, killing all of the Time Lords and Daleks. He believed he was the last of the Time Lords, until he discovered that the Master had also survived. Jenny, who was created artificially in "The Doctor's Daughter," is not a true Time Lord. For many years, the Doctor felt sorry for destroying Gallifrey. In the 2013 episode "The Day of the Doctor", the Doctor learns that he did not actually destroy his planet, but that he had moved it to another universe.
As of 2018, the Doctor has been played by fourteen actors. They are William Hartnell, Patrick Troughton, John Pertwee, Tom Baker, Peter Davison, Colin Baker, Sylvester McCoy, Paul McGann, John Hurt, Christopher Eccleston, David Tennant, Matt Smith, Peter Capaldi and Jodie Whittaker.
When Time Lords are dying, they "regenerate." This causes a Time Lord's body to completely change, healing itself at the same time. Each time this happens, Time Lords have a different appearance and a different personality. Even with such big changes, Time Lords do not become different people, and will keep their memories each time they "regenerate." This periodic change makes them live a very long time.
A Time Lord is believed to only be able to regenerate 12 times. This means that Time Lords can have a total of 13 different incarnations. This line became stuck in the public consciousness despite not often being repeated, and was recognised by producers of the show as a plot obstacle for when the show finally had to regenerate the Doctor a thirteenth time. The episode "The Time of the Doctor" depicted the Doctor acquiring a new cycle of regenerations, starting from the Twelfth Doctor, due to the Eleventh Doctor being the product of the Doctor's twelfth regeneration from his original set.
A criminal incarnation of the Doctor was somehow spawned between his 12th and final lives - the 'Valeyard'. It tried to sacrifice the sixth Doctor so that he could obtain more "regenerations," allowing himself to live even longer.
The Master was already in his 13th life when he was introduced to the series. His 14th and 15th (and possibly later) incarnations were obtained by taking over the bodies of innocent victims. When the character returned to the show in 2007, the Master was in his 16th (or later) incarnation. Soon, he regenerates into his (~)17th incarnation. Later, he explains that the Time Lords resurrected him to be a great soldier when the Time Lords were fighting the Daleks in the Time War. It is likely that, having been resurrected, he had 12 more regenerations available to him.
A Time Lord can choose not to regenerate. It appears that the process happens all on its own when a Time Lord is dying. But, it can be stopped if the Time Lord does not want to regenerate. This was seen when the (~)17th incarnation of the Master chose to die from a gunshot wound instead of living on as a prisoner in the Doctor's TARDIS.
A Time Lord's body makes a huge amount of energy when regenerating. There is so much of this "regeneration energy" that a Time Lord can regrow a body part that gets removed, as long as it happens soon enough after regenerating. When the Doctor regenerated into his 10th incarnation, his hand was cut off in a sword fight. Because it had been less than 15 hours since he had regenerated into this incarnation, he was able to quickly grow a new hand.
If a Time Lord has kept a part of his or her body that had been removed (like the 10th Doctor's hand, from before), it can be used to keep a Time Lord from changing during regeneration. The 10th incarnation of the Doctor kept the hand that was cut off in the sword fight in a jar on board the TARDIS. Eventually, he was shot by a Dalek, and his body began the regeneration process. After his body had finished healing, but before his body could change into a new one, the Doctor sent all of the extra energy into the hand in the jar.
Concentration camp
A concentration camp (or internment camp) is a place where a government forces people to live without trial. Usually, those people belong to groups the government does not like. The term means to confine (keep in a secure manner) "enemy citizens in wartime or terrorism suspects".
Some governments put people in concentration camps because they belong to a certain religion, race, or ethnic group.
Usually, people are sent to concentration camps without having had a trial or being found guilty of a crime.
Sometimes, governments send people to concentration camps to do forced labor or to be killed. For example, concentration camps were run by Nazi Germany and the Soviet Union during World War II. The Nazis used concentration camps to kill millions of people in The Holocaust and force many others to work as slaves. However, many other countries have used concentration camps during wars or times of trouble.
The first modern concentration camps in the United States were created in 1838. Around this time, the United States was getting bigger. However, Native Americans lived in the lands that the United States wanted to take over.
In 1830, the United States Congress and President Andrew Jackson had passed a law called the Indian Removal Act. This law said that all Native Americans had to leave the United States and move to "Indian Territory," west of the Mississippi River. However, many Cherokee people would not leave their lands. In May 1838, the United States government decided to force the Cherokee to leave the United States.
First, soldiers forced about 17,000 Cherokee people, and 2,000 of their African-American slaves, into concentration camps, where they had to live during the summer of 1838. 353 Cherokee people died in the camps from dysentery and other diseases. Finally, the Cherokee were forced to travel to the area that is now Oklahoma. (At the time, Oklahoma was not in the United States.) The government also forced other Native American tribes to leave their lands and move west.
Soon, many people from the United States started to move west. Now the United States was moving into Native American lands again. Starting around the 1860s, many Native American tribes fought back. These fights are now called the Indian Wars. The United States government reacted by forcing Native Americans to leave their lands again and move into concentration camps. The government called these camps "Indian reservations." (They were called "reservations" because some land had been put aside, or "reserved," for the Native Americans.) However, Native Americans were not allowed to leave their reservations. On some reservations, many people, especially children, died from hunger and sickness.
During the American Civil War in the 1860s, soldiers who had been captured were sometimes put in camps. These camps were meant to be prisoner of war (POW) camps, with good conditions. However, as the war went on, both the Union and the Confederacy captured more enemy soldiers. The camps became very crowded, with terrible conditions. There was not enough food, and many men died from hunger. Also, there was also very little sanitation, which made it easy for diseases to spread. Many prisoners died from these diseases.